This is another common misconception on lend lease. It did of course help immensely but bear in mind that Germany invaded Russia before the USA entered the war in Dec 1941. Russia were only declared eligible for lend lease in Nov 1941 (6 months after Germany invaded). By the time the USA entered the war in Dec 1941, Germany had already burnt itself out trying to take Moscow and once they had failed to do so, a long protracted war with Russia was all but guaranteed (note, Germany had still not fully mobilised until 1942).
The majority of lend lease stuff did not start appearing until mid to late 1942, of course some was delivered earlier but not enough to impact the course of the war in the east during its most critical stage. By the time lend lease material had arrived in significant numbers, Russia had already ground the Germans into a stalemate and were starting to more than hold their own.
I’m no fan of soviet Russia but it seems to be a common theme that the west has always tried to take credit for “saving them” from almost certain defeat against the Nazis .