It's very difficult to get to a stalemate on the eastern front, but not totally impossible. Get the Germans to notice the rather obvious Soviet buildups that proceeded the Soviet Stalingrad offensives, and that helps a lot.
Given a competent German leadership and several days notice, the Germans could probably have saved most of the troops and equipment lost at Stalingrad. That would have been very significant because the Germans had stripped away a lot of trucks and tanks from the rest of the army in order to make their army in the south mobile again in 1942. They lost a lot of that stuff at Stalingrad, and never regained the ability to do large-scale strategic movements.
Historically, every Soviet advance made the Soviets stronger for the next offensive, for several reasons. They regained manpower from the reconquered territories, in spite of German efforts to get men of military age out. They regained breadbasket regions, which was very important because the parts of the Soviet Union in Soviet hands as of fall 1942 was incapable of feeding itself long-term, and while US Lend-Lease food made a difference, there were limits to our ability to do that, especially if we were going to keep them supplied with Avgas, rubber, trucks, trains, etc.
The Soviets also gained some subtle advantages from their advances, which included a lot more partisans. The unfortunate reality is that most humans, which includes Russians, try very hard to end up on the winning side, which meant that partisans became much stronger when it became apparent that the Soviets were winning.