This is a difficult one because Jacksonville have already beat Pittsburgh..
That being said, Antonio Brown looks to be back in for the playoffs and with the veteran Ben at QB it will be difficult to stop the pass play. I'm not going to say that Jacksonville can't stop them (like they did earlier this year) but it will be difficult for Bortles to keep up with the offense that Pittsburgh has.
If Jacksonville can keep playing their explosive defense and get some sacks in key situations (3rd downs) and hold them to field goals, it could be a tight game. Bortles just hasn't performed lately but that doesn't rule him out for this matchup.