As others have said, it is impossible to know for sure.
To some degree it depends on the success that the Germans would have had in taking control of the conquered lands, and how coercive they would have been in enslaving the conquered countries. For example, if German had taken England (before taking the rest of France and Russia) then they would have had access to England’s significant manufacturing capacity (steel, ships, etc.). They could have taken that manufacturing ability to make more and better armaments which then they would have used for taking over Russia all the say to Asia.
But that assumes that the Germans were prepared to occupy and take lots of losses in England (which would have fought back), and it is only speculation if Germany would have thought that worthwhile.
One thing we can say for sure is that if the US had not assisted Russia (Stalin) than Russia would have been lost,
But so much of this is guesswork, because we don’t know what Germany’s strategy might have been if they had won in various battles, and lost in others.