Update: per ESPN The game averaged 26.029 million across its networks (includes MegaCasts) and streaming.
Per ESPN, Clemson-Alabama drew a combined (includes Megacasts on ESPN2 & ESPNU) 15.3 overnight rating for Clemson’s dramatic win over Alabama in the CFP Championship game. I haven’t seen the ESPN-only overnight rating but last year’s combined overnight was 16.0 (with 15.8 of it being on ESPN) so despite the great game the overnight rating is definitely down year over year.
Here are the local market ratings for the game:
Viewership should be released later today. More info including streaming via ESPN.