The United States did contribute to the Eastern Front, but I wouldn`t say they "saved" the USSR. The turning point of the Eastern Front was on 2 February 1942 after Stalingrad, and the Western Allies only landed in Sicily and Normandy the following years. As for the lend-lease, well, it only made up about 8% of the Red Army`s total war materiel.

Description: 1. Hitler's best generals (i.e. Erwin Rommel) were stationed at different fronts, such as in North Africa, southern Italy, the Western Front and the Pacific, whereas all the Red generals (such as Zhukov and Rokossovsky) were stationed at the Eastern Front. 2. The Germans' factories were 14,000 kilometres from the frontline in 1942. 3. Blitzkrieg ran on the resources and war materiel acquired from enemy territories, and Stalin ordered that factories be destroyed before the Nazis could capture them. 4. The Red Army had air support from the United States, Canada, United Kingdom, Free France, Australia, and New Zealand almost from the get-go. 5. Nazi Germany's allies (Finland, Romania, Bulgaria) switched sides in 1944. 5. Poland and Czechoslovakia offered their support after being liberated. 6. The USSR received lend-lease from the United States. 7. Hitler's bad military decisions. 7.1. Hitler refusing to let the 6th Army fall back at Stalingrad. 7.2. The exhaustion of most of the Germans' remaining supplies at the Battle of the Bulge, which Hitler DIRECTLY ORDERED. 7.3. Hitler not listening to his generals. 7.4. Hitler promoting himself to Oberkommando der Wehrmacht, despite having minimal experience as a military commander. 8. Hitler's physical and mental health. 8.1. Hitler was receiving prescriptions of cocaine. 8.2. The numerous assassination attempts on Hitler's life, both during and prior to the war. 9. The Battle of Stalingrad. 11. The Battle of Kursk. 12. Stalin's Ten Blows. 13. Hitler having to redirect his troops to southern Italy due to the invasion of Sicily.