Saurik is not minting money. He's comfortable, I'm sure, but he's not getting rich. Most Cydia revenues (which are a small percentage of only the paid apps...he doesn't even put ads in Cydia) go right into the company.
Also, Saurik is intimately involved in every jailbreak released. It is he who provides the Cydia bootstrap that's essential to making your jailbreak actually do something. And without his constant work on MobileSubstrate NONE of the most useful Cydia tweaks would be possible.
I'm pretty sure I see ads in every page of any app/tweak I see.