'"I want to tell you what, from the Russian point of view, the president and the United States have done for victory in this war," Stalin said. "The most important things in this war are the machines.... The United States is a country of machines. Without the machines we received through Lend-Lease, we would have lost the war."...
'"If the United States had not helped us, we would not have won the war," [Nikita Khrushchev] wrote in his memoirs. "One-on-one against Hitler's Germany, we would not have withstood its onslaught and would have lost the war. No one talks about this officially, and Stalin never, I think, left any written traces of his opinion, but I can say that he expressed this view several times in conversations with me."...
'In 1963, KGB monitoring recorded Soviet Marshal Georgy Zhukov saying: "People say that the allies didn't help us. But it cannot be denied that the Americans sent us materiel without which we could not have formed our reserves or continued the war. The Americans provided vital explosives and gunpowder. And how much steel! Could we really have set up the production of our tanks without American steel? And now they are saying that we had plenty of everything on our own."'
The counter-argument was that this was propaganda, but I don't accept that.
https://www.rferl.org/a/did-us-lend-lease-aid-tip-the-balanc...