Magnate, in the sense of Morgan and Vanderbilt, who are very well known for controlling a vast majority of influence in their respective industries. Here, "chick magnate" refers to one man's near-domination of the female population in an average city-sized geographical area.
Girl you're dating: "Hey, do you know Riff Bankston?
You: "Oh, that chick magnate? What about him?"
GYD: "I think we should have a threesome with him."