Maybe new people that are not in bitcoin gambling yet, and you can show them how to buy coins and then you can register them on site you wish. I dont see other possibility for you to have good affiliates.
I have couple referrals on some faucets, its people from my facebook, but they are not so active and I dont have some big earning from them.
But only if you have good affiliates though, most people are smart enough to play not from your link although they know it because they dont want to give you the profit although they dont lose anything but to give people money it just hard for some people. For us may be it is benefits because we dont need to do anything to get the income, for other that under our affiliates it will sure be problem because they need to gambling to get earning unless they find a good affiliates too