The bottom line is the Bengals control their own destiny entirely--even if they lose to Dallas or Philly. If the Bengals beat EITHER Dallas or Philly, and then beat Pittsburgh and Baltimore, they make the playoffs.
However, if the Bengals beat Philly, Dallas and Pittsburgh, but lose to Baltimore, and Pittsburgh wins its other 3 games, then Pittsburgh would get the wild card spot over the Bengals (assuming Baltimore and Indy don't collapse, in which case there are ways both Pittsburgh and Cincy can make it).
All of these scenarios can be figured out here:
Bengals actually have a not-all-that-improbable path to the division title. Baltimore plays the Giants, Denver and Washington. If they lose two of those games, and the Bengals win out, then the last game of the year is for the AFC North title. Of course, the changes of the Bengals beating Pittsburgh are pretty slim, so I'm not getting my hopes up.