In plain words
Among deceivers I am gambling; I am the splendour of the splendid. I am victory, determination, and the sattva of those endowed with sattva.
Word for word
Gambling of those who deceive I am; splendour of the splendid [am] I; victory I am, resolve I am, the sattva of those endowed with sattva [am] I.
The commentators
Bhagavadgītābhāṣyam· bhāṣya
द्यूतम् अक्षदेवनादिलक्षणं छलयतां छलस्य कर्तॄणाम् अस्मि । तेजस्विनां तेजः अहम् । जयः अस्मि जेतॄणाम् , व्यवसायः अस्मि व्यवसायिनाम् , सत्त्वं सत्त्ववतां सात्त्विकानाम् अहम् ॥ ३६ ॥
In plain words
"I am gambling" — dice-play and games of that kind — "of cheats," that is, of those who practise deceit. Of the brilliant, I am the brilliance. I am victory, and it is the victors' victory; I am resolve, and it is the resolve of the resolute; I am sattva, the sattva of those who have it — of people in whom sattva rules.
Close to the Sanskrit
Gambling, characterized by dice-play and the like, of the cheats — of the doers of deceit — I am. Of the brilliant, the brilliance am I. Victory I am, of the conquerors; resolve I am, of the resolute; sattva I am, of those possessing sattva, of the sāttvika ones.