The England winger continues to be linked with a summer move to Manchester United.
But Favre says: "Of course I would be very, very lucky if he continues to play for us.
"But that is unfortunately not in my hands."
Favre is also confident of being in charge of BVB next season.
The Swiss added: "I felt it internally and I'm happy about it. And I've always dealt with public pressure very professionally in my career."