Per the Daily Caller, Tucker Carlson will replace Megyn Kelly in Fox News 9pm timeslot:

Just days after Kelly announced she was leaving the network after 12 years for a position at NBC News, news broke that Fox News is replacing “The Kelly File” with Carlson’s new show “Tucker Carlson Tonight.” Though he had taken over Greta Van Susteren’s slot at 7 p.m. EST, Carlson will now move to 9 p.m. EST.

Since the show first aired in November, “Tucker Carlson Tonight” has given the network a historic ratings boost. At least 3.7 million watched its debut.
 

Martha MacCallum will take over Calrson’s 7pm slot.