Answer

If a person’s majority income is lawful and less than half is unlawful, it would be permissible to eat from the food purchased with such income.

If a person’s majority income is unlawful then there are two possibilities:

If he clearly states that the food provided was acquired through halal wealth one may eat the food. However, if this were not the case it would not be permissible to eat the food. (Fatawa Hindiyyah p.343 v.5)