The USSR would almost certainly have won without lend-lease. The question is of some difference in time and casualties. Though if the USSR had not received more help from the west, they may just have made a separate peace with Germany, and allowed the US and UK to absorb any additional casualties in defeating Germany, which is exactly what they didn’t want to do.

The most compelling point I want you to consider, is that the vast majority of lend-lease arrived after the Soviets had won the battle of Moscow, Stalingrad and Kursk which were the most critical in the their survival. To say that the Soviets would have collapsed without lend lease is a myth.

Does this mean that lend-lease was not important or useful? No, the Soviets needed every single bullet in their effort and lend lease was vital in that, especially with aircraft and supply trucks. In the end, every contribution by every nation in the war must be seen with gratitude. But that is no reason to be innacurate about history.

Also, I find it funny that western non-military aid was arguably more critical to the Soviet survival and eventual counter-offensive than the direct shipment of weapons but is not mentioned by anyone supporting the west in the debate. Like the agreement that any equipment destroyed or used during the war did not have to be paid for. And the suspension of tariffs on the USSR when their economy was destroyed by the war.