We won't clinch with a win on Thursday. But we'd be up 4 games in the division with 5 to go, so it'd almost be a certainty if we can knock off the Lions.
This game could either spring board us or possibly hurt us, especially with that Dallas game looming. If we win on Thursday, even a loss to Dallas wouldn't hurt us to badly. If we lose to the Lions and then lose to the Cowboys, our 3 game lead could quickly shrink to a single game depending on what the Lions do, not to mention they'd have the tiebreaker and a two game lead in divisional record over us.