Poultry has given him great profit.
Is this sentence grammatically correct? What do you think is the correct use if this isn't correct?
It would help to add a bit more in there like "poultry production," "the poultry business," "the poultry farm" etc.
But since you're asking about its grammatical accuracy, the original sentence is fine.
It could also be used to emphasize the distinction "Poultry (not cattle) has given him great profit."