Les Bleus share Group I with reigning world and European champions Spain and fell three points behind in second place following Friday's frustrating goalless draw with Georgia, their fifth successive game without scoring.
With Spain not in action on Tuesday, Didier Deschamps' side will be desperate for victory in Belarus to keep up the pressure.
Bayern Munich star Ribery said: "We know we have only a very slender chance of going through as group winners, so we must make sure we are among the best second-placed sides. That's why we have to win this game.
"This team has to go to Brazil, whatever the route. The play-offs are okay by me as long as we get through."
The other game in the group sees Georgia host Finland in Tbilisi.
The visitors lie third in the group on six points, one ahead of their opponents, and defender Teemu Tainio is confident they can silence the raucous home crowd and get a result.
Tainio told the Football Association of Finland's official website, www.palloliitto.fi: "We have already seen in Finland, it was not an easy game.
"They took a point off France which shows that Georgia are a good team, especially at home. Their fans are fanatical and make it a difficult place to go.
"This is not new to us, we know about it. We will go there to play our own game and get some points."