Colbert was already scheduled to be taken off the air and kimmels numbers were in the dump until the drama with Trump gave him a small enough boost in ratings. Never watched Colbert, haven't seen any clips that made me think he was funny. Kimmel was funny when he was doing blackface Carl Malone and making chicks in bikinis bounce on trampolines, once he got away from Adam Carrola it became evident who the comedian of the two is as Kimmel seemed to swallow liberal balls and make that his whole identity.
colbert had the highest rated late night show as far as I know. His removal was after the merger and pressure from Trump.
He pressured Kimmel and if it wasn't for backlash I am sure he would still be off the air.