Some casinos will pay you a percentage of their profits from players for the entire time that player is a member of that casino. Some casinos won't pay you at all. What we have done here is listed several webmaster programs that are highly rated, as well as those that are really substandard. Some have a flat rate. Be realistic and expect to be making profits in the lower end of the spectrum.
Some sites list profits only.
Some sites like Casino Treasure and The Sands of the Caribbean go into great detail. At a minimun, you need to know how many players have signed up through your site. That way you can judge whether or not certain marketing strategies have worked. Download their software and play their games. Also, most casinos have newsletters for their customers, but not their affiliates.