That's a wee bit revisionistic. If any of one country is to be portrayed as defeating the Nazis, it should probably be the USSR, and that at an astronomic cost.
https://en.wikipedia.org/wiki/Lend-Lease#Significance:
”I would like to express my candid opinion about Stalin’s views on whether the Red Army and the Soviet Union could have coped with Nazi Germany and survived the war without aid from the United States and Britain. First, I would like to tell about some remarks Stalin made and repeated several times when we were "discussing freely" among ourselves. He stated bluntly that if the United States had not helped us, we would not have won the war”
Yes, that whole page may be biased, but Stalingrad was ‘only’ the mental turning point, but only after Kursk, 7-8 months later, was the German collapse unavoidable. Even then, lend lease didn’t contribute much percentage-wise, but it doesn’t take a huge amount to tip a well balanced battle.
Also, the allied landing in Sicily forced Hitler to move forces from Kursk, and that might not have taken place that early without land lease aid to the British.