Stephen Colbert is not funny.
He can be a small part of something funny—but only by being a caricature of himself.
Strangers with Candy was funny, and he was a part of that—but his character was a caricature his actual self.
When he is allowed to go off on his own, he fails utterly. He is a robot who can barely read a teleprompter.
So no—he is not funny.
He can be slightly funny as an object of ridicule, but not in any other capacity.
Soon the bucks will be gone, but the egg on his face will remain.