BhG 3.33

syntax

jñānavān api (even one has knowledge) svasyāḥ (of own’s own) prakṛteḥ (of the  nature) sadṛśam (accordingly) ceṣṭate (he acts),
[tasmād] (therefore) bhūtāni (creatures) prakṛtiṁ (the nature) yānti (they attain).
nigrahaḥ (suppression) kiṁ (what?) kariṣyati (it will do).

grammar

sadṛśam	–	av. – accordingly (from: sadṛśa – like, resembling, suitably: requires genitive);
ceṣṭate	–	√ceṣṭ (to move, to endeavour, to act) Praes. Ā 1v.1 – he acts, he endeavours;
svasyāḥ	–	sva sn. 6n.1 f. – of one’s own;
prakṛteḥ	–	prakṛti 6n.1 f. – of nature, primary substance, original cause (from: pra-√kṛ – to produce);
jñāna-vān	–	jñāna-vant 1n.1 m. – who has knowledge (from: √jñā – to know, to understand, jñāna – knowledge, wisdom, intelligence; -mant / -vant – suffix denoting one who possesses);
api	–	av. – although, moreover, besides, even;
prakṛtim	–	prakṛti 2n.1 f. – nature, primary substance, original cause (from: pra-√kṛ – to produce);
yānti	–	√yā (to go, to attain) Praes. P 1v.3 – they go, they attain;
bhūtāni	–	bhūta (√bhū – to be) PP 1n.3 n. – beings, creatures;
nigrahaḥ	–	nigraha 1n.1 m. – suppression, control (from: ni-√grah – to hold back, to control);
kim	–	kim sn. 2n.1 n. – what?
kariṣyati	–	√kṛ (to do) Fut. P 1v.1 – it will do;

Śāṃkara

The key:
an excerpt from the commented verse
quotes from the scriptures
starting polemic

Influence of man’s nature on his conduct. Then, why do they, not following Thy doctrine, perform others duties and neglect their own? Thus opposed to Thee, why are they not afraid of the sin of transgressing Thy command?		kasmāt punaḥ kāraṇāt tvadīyaṃ mataṃ nānutiṣṭhantaḥ para-dharmān anutiṣṭhanti? sva-dharmaṃ ca nānuvartante? tvat-pratikūlāḥ kathaṃ na bibhyati tvac-chāsanātikrama-doṣāt ? tatrāha —
Even the man of knowledge acts in conformity with his own nature; (all) beings follow (their) nature; what shall coercion avail?		sadṛśaṃ ceṣṭate svasyāḥ prakṛter jñānavān api | prakṛtiṃ yānti bhūtāni nigrahaḥ kiṃ kariṣyati ||3.33||
Nature (prakṛti) is the samskara (the latent self-reproductive impression of the past acts of dharma and a-dharma) manifesting itself at the commencement of the present birth.		sadṛśam anurūpaṃ ceṣṭate ceṣṭāṃ karoti | kasyāḥ? svasyāḥ svakīyāyāḥ prakṛteḥ | prakṛtir nāma pūrva-kṛta-dharmādharmādi-saṃskārā vartamāna-janmādāv abhivyaktāḥ | sā prakṛtiḥ | tasyāḥ sadṛśam eva sarvo jantur jñānavān api ceṣṭate, kiṃ punar mūrkhaḥ?
Even the man of knowledge acts according to his own nature; it needs no saying that an ignorant man acts according to his own nature. Thus all living beings follow their own nature. What shall coercion in the shape of prohibition avail? That is to say, to Me or to anybody else, nature is irresistible.		tasmāt prakṛtiṃ yānty anugacchanti bhūtāni prāṇinaḥ | nigraho niṣedha-rūpaḥ kiṃ kariṣyati mama vānyasya vā? durnigrahā prakṛtir iti vākya-śeṣaḥ ||3.33||

Rāmānuja

evaṃ prakṛtisaṃsargiṇas tadguṇodrekakṛtaṃ kartṛtvam, tac ca paramapuruṣāyattam ity anusandhāya karmayogayogyena jñānayogayogyena ca karmayogasya suśakatvād apramādatvād antargatātmajñānatayā nirapekṣatvāt, itarasya duśśakatvāt sapramādatvāc śarīradhāraṇādyarthatayā karmāpekṣatvāt karmayoga eva kartavyaḥ; vyapadeśyasya tu viśeṣataḥ sa eva kartavyaḥ iti coktam / ataḥ param adhyāyaśeṣeṇa jñānayogasya duśśakatayā sapramādatocyate

prakṛtiviviktam īdṛśam ātmasvarūpam, tad eva sarvadānusandheyam iti ca śāstrāṇi pratipādayantīti jñānavān api svasyāḥ prakṛteḥ prācīnavāsanāyās sadṛśaṃ prākṛtaviṣayeṣv eva ceṣṭate; kutaḥ? prakṛtiṃ yānti bhūtāni acitsaṃsṛṣṭā jantavo ‚nādikālapravṛttavāsanām evānuyānti; tāni vāsanānuyāyīni bhūtāni śāstrakṛto nigrahaḥ kiṃ kariṣyati

Śrīdhara

nanu tarhi mahā-phalatvād indriyāṇi nigṛhya niṣkāmāḥ santaḥ sarve ‚pi svadharmam eva kiṃ nānutiṣṭhanti ? tatrāha sadṛśam iti | prakṛtiḥ prācīna-karma-saṃskārādhīnaḥ svabhāvaḥ | svasyāḥ svakīyāyāḥ prakṛteḥ svabhāvasya sadṛśam anurūpam eva guṇa-doṣa-jñānavān api ceṣṭate | kiṃ punar vaktavyam ajñaś ceṣṭata iti | yasmād bhūtāni sarve ‚pi prāṇinaḥ prakṛtiṃ yānty anuvartante | evaṃ ca sati indriya-nigrahaḥ kiṃ kariṣyati ? prakṛter balīyastvād ity arthaḥ

Madhusūdana

nanu rājña iva tava śāsanātikrame bhayaṃ paśyantaḥ katham asūyantas tava mataṃ nānuvartante kathaṃ vā sarva-puruṣārtha-sādhane pratikūlā bhavantīty ata āha sadṛśam iti | prakṛtir nāma prāg-janma-kṛta-dharmādharma-jñānecchādi-saṃskāro vartamāna-janmany abhivyaktaḥ sarvato balavān taṃ vidyā-karmaṇī samanvārabhete pūrva-prajñā ca iti śruti-pramāṇakaḥ | tasyāḥ svakīyāyāḥ prakṛteḥ sadṛśam anurūpam eva sarvo jantur jñānavān brahmavid api paśv-ādibhiś cāviśeṣāt iti nyāyāt | guṇa-doṣa-jñānavān vā ceṣṭate kiṃ punar mūrkhaḥ | tasmād bhūtāni sarve prāṇinaḥ prakṛtiṃ yānty anuvartante puruṣārtha-bhraṃśa-hetu-bhūtām api | tatra mama vā rājño vā nigrahaḥ kiṃ kariṣyati | rāgautkaṭyena duritān nivartayituṃ na śaknotīty arthaḥ | mahā-naraka-sādhanatvaṃ jñātvāpi durvāsanā-prābalyāt pāpeṣu pravartamānā na mac-chvāsanātikrama-doṣād bibhyatīti bhāvaḥ

Viśvanātha

nanu rājña iva tava parameśvarasya matam ananutiṣṭhanto rāja-kṛtād iva tva-kṛtān nigrahāt kiṃ na vibhāti ? satyam | ye khalu indriyāṇi cārayanto vartante, te vivvekino ‚pi rājñaḥ parameśvarasya ca śāsanaṃ mantuṃ na śaknuvanti | tathaiva teṣāṃ svabhāvo ‚bhūd ity āha sadṛśam iti | jñānavān api evaṃ pāpe kṛte saty evaṃ narako bhaviṣyaty evaṃ rāja-daṇḍo bhaviṣyati | evaṃ duryaśaś ca bhaviṣyatīti vivekavān api svasyāḥ prakṛteḥ cirantana-pāpābhyāsottha-duḥkha-bhārasya sadṛśam anurūpam eva ceṣṭate | tasmāt prakṛtiṃ svabhāvaṃ yānty anusaranti | tatra nigrahas tac-chāstra-dvārā mat-kṛto rāja-kṛto vā tenāśuddha-cittān ukta-lakṣaṇo niṣkāma-karma-yogaḥ śuddha-cittān jñāna-yogaś ca saṃskartuṃ prabodhayituṃ ca śaknoti, na tv atyantāśuddha-cittān, kintu tān api pāpiṣṭha-svabhāvān yādṛcchika-mat-kṛpottha-bhakti-yoga eva uddhartuṃ prabhavet | yad uktaṃ skānde –

aho dhanyo ‚si devarṣe kṛpayā yasya te kṣaṇāt |
nīco ‚py utpulako lebhe lubdhako ratim ucyate

Baladeva

nanu sarveśvarasya te matam atikramatāṃ daṇḍaḥ śāstreṇocyate tasmāt te kim u na bibhyati ity āha sadṛśam iti | prakṛtir anādi-kāla-pravṛttyā sva-durvāsanā tasyāḥ svīyāyāḥ sadṛśam anurūpam eva jñānavān śāstroktaṃ daṇḍaṃ jānann api janaś ceṣṭate pravartate kim utājñaḥ | tato bhūtāni sarve janāḥ prakṛtiṃ puruṣārtha-vibhraṃśa-hetu-bhūtām api tāṃ yānty anusaranti | tatra nigrahaḥ śāstra-jñāno ‚pi daṇḍaḥ sat-prasaṅga-śūnyasya kiṃ kariṣyati ? durvāsanāyāḥ prābalyatāṃ nivartayituṃ na śakṣyatīty arthaḥ | sat-prasaṅga-sahitasya tu tāṃ prabalām api nihanti – santa evāsya chindanti mano-vyasanam uktibhiḥ [BhP 11.26.26] ity ādi smṛtibhyaḥ