The 20-year-old joined Les Dogues in January for £13m but, having impressed during France's U20 World Cup win this summer, is thought to be keen on forcing through a move away from the Stade Pierre Mauroy.
However, Seydoux is adamant that Thauvin, who has previously caught the eye of Arsenal and Newcastle United, will remain with Lille for the rest of the season.
"Unfortunately I don't have a crystal ball, but yes I'm 99.9% sure," Seydoux told L'Equipe. "There's no reason for him to leave Lille. And the way in which things are happening have merely shown me I'm right. Now, if we give in to whatever kind of pressure, the power wouldn't be in the right place.
"He's making his own problems. I think his advisors are not the best in the world. It should be very simple, and it's a bit too complicated for me. The real victim is Florian Thauvin, who's not playing football.
"It's troubling for him. He's hurting himself. Lille lived before Florian Thauvin and will live after Florian Thauvin. The question that needs asking is why the advice he's getting is so bad. We're in a normal world, he's not being exploited, he's in a rather good club with good ambitions. I think Florian has everything to gain in closing this chapter and putting on his boots."
Marseille are thought to be keen on signing Thauvin.