I'll let others answer for Sosua... but if Cabarete's not too far, if you're travelling from Sosua there's Ocean Sands Casino on the main road to the right just past center of Cabarete. Would be hard to miss if you're looking for it.
Playa Chiquita Casino. It's a small Casino but they have BJ, Roulette and Poker. And, it's only a 5 minute moto concho ride from the strip. I'll be there myself real soon! Can't wait...