With reference to another commenter my research finds that on September 22, roughly twenty Jewish Red Army POWs arrived at Sobibor on a transport from the Minsk Ghetto and were selected for labor. Among them was Alexander Pechersky.
According to the Holocaust Museum the camp was dismantled after the uprising. So the film seems to be reasonably accurate on those issues.
There were 58 known survivors of the escape.
You see Alexander carrying Luka in his arms towards the end of the film. This is artistic licence. Nobody knows what became of her.