Apple has updated the prominent Watch Now section of the TV app to feature live news channels. iPhone and iPad users with iOS 11.2.5 and Apple TV users with tvOS 11.2.5 will see the change immediately.
Finding the new section is easy. From the Watch Now tab, scroll down past the Up Next section to the What to Watch recommendations. This list is dynamic, but it currently shows a row of TV shows and movies, then a PyeongChang 2018 row for Winter Olympics coverage. Below that is the new News row. Multiple channels are represented, with a red "Live" banner on the thumbnail image.