The chicken here is the same bird as steamed chicken rice, just cooked in a soy stock instead of poached. Braising renders some fat out of the skin, which is why a plate at 551 comes in a bit under steamed chicken rice at 607. 100g of soy chicken with skin is about 190 calories. The soy gravy poured on top has sugar in it, about 35 calories a spoon. The rice is the same 290 calories for 200g because it is still cooked in chicken fat.
The most famous version, the hawker stall that got a Michelin star, sells the plate at about S$3.80 with a generous mound of rice. That plate is closer to 600 because the rice is bigger. The chicken portion is what you would expect, about 100 to 120g. So the cheap famous plate is heavier than the number above, not lighter.
Breast or thigh is a real choice with soy chicken. Thigh with skin is about 210 calories per 100g in soy stock. Breast with skin about 170, breast with the skin peeled about 130. Ask for breast, peel the skin, and the whole plate drops to about 490 with more protein than before.