He'll unquestionably make more as Late Night Host tho.....Leno & Letterman made in the ballpark of $15-30 million a year just in salary as hosts, plus the added revenue such a thing brings for ones production company, increased value of one's brand, etc etc.
It's also why he's quite obviously (imo) playing the Leno game, of trying to appeal to as base an audience as possible to maximize his viewership & revenue generation.
Business wise, it's a brilliant move......and while many knocked Lenoh for it, he took way more pride in being able to appeal to a mass audience than he did making the small niche of the alt comedy community laugh, back when he was buddies with Letterman and was a "comedians comedian".
Colbert doesn't care that I'm less interested, he cares that Joe Q Sixpack in Wyoming is tuning in 5 nights a week.