The Steelers lost their last game against them, 16-10, but the defense probably had their best game of the season.
The Bengals defense is very good, but at the same time, they are not invincible, as they have given 34 points to the Cardinals in week 11.
Roethlisberger was probably rusty in the game against the Bengals in week 8 but since that game, the Steelers have scored 143 points in 4 games.
Roethlisberger is 10-2 in his career in Cincinnati, so I think the Steelers will win this game if they are not beat themselves with the turnovers as at Seattle