It’s implicit in your statement. Casinos employ many people,no doubt, but the effect on the economy were they to be shut down could be positive, negative, or neutral, depending on where the money then goes. Do they employ more people per dollar spent there than, say, a restaurant, an educational institution, a bar, or department store? I don’t know, but I would suspect the effect of removing easy access to gambling would be on the whole positive.
Providing jobs that would not otherwise exist is an economic good, viewed in isolation, but providing them via an activity that is a social harm is not. See the fallacy of the broken window.