Being an affiliate manager is not that easy but once you get into it, it is kind of addictive. The salaries range from 1k a month to over a million a year (I know of one manager on this outside of gaming) depending on the affiliate managers.
Most programs work with managers on;
1) strict salary only, and a small target bonus
2) more experienced managers ask for a salary and a monthly cut of the action based on the growth
http://en.wikipedia.org/wiki/Affiliate_manager is a good indication of what the affiliate managers role portrays.