If my math is correct, only half the Round of 16 games will be shown on TNT, the remainder will be online only (I think). Trying to remember if all Round of 16 games are played in the same week or if they alternate.
One of the biggest changes that soccer fans will notice with the UEFA Champions League coverage for the 2018/19 season is the kickoff time. Instead of most of the matches kicking off at 2:45pm ET on a UEFA Champions League matchday, they will be begin at either 12:55pm ET or 3pm ET, which will allow broadcasters to feature a double-header of soccer coverage (see below):
• Group Stage: Tuesday, Sept. 18, through Wednesday, Dec. 12, with weekly matches held Tuesdays and Wednesdays at 12:55 p.m. ET and 3 p.m. ET. All matches will be available on B/R Live, with one match per game window (two each day) televised on TNT, • Round of 16: Tuesday, Feb. 12, through Wednesday, March 13, with matches on B/R Live and TNT each Tuesday and Wednesday at 3 p.m. ET • Quarterfinals: Tuesday-Wednesday, April 9-10 and April 16-17, with live coverage on B/R Live and TNT at 3 p.m. ET • Semifinals: Tuesday-Wednesday, April 30-May 1 and May 7-8, with matches on B/R Live and TNT at 3 p.m. ET • Final: Saturday, June 1, at 3 p.m. ET on B/R Live and TNT
http://worldsoccertalk.com/where-to-watch-uefa-champions-league-and-europa-league-on-us-tv-and-internet/