Lend lease was hugely dynamic in the Eastern Front. Aside from the vast material aid supplied to the Soviets, the aid also served as a morale boost to the populace at large.

The United States gave approximately $12 billion worth of materials in lend lease to the Soviet Union throughout the war; this is almost $200 billion worth with inflation.

Items of note that were given as aid:

400,000 trucks and jeeps

7,000 tanks

5,000 other types of armored vehicle

nearly 12,000 aircraft

3 million tons of petroleum

4.5 million tons of foodstuffs (American rations became so ubiquitous that in parts of the Red Army, soldiers would joke they were "opening the second front" when eating American food).

All in all, American aid to the Soviets was undeniably massive. What is a much harder speculative question to answer is how important it was overall to the success of the Eastern Front, and if the Soviets could have coped without. People come to wildly different conclusions on this. I remember my old warfare history professor giving his assertion that the Red Army would still have eventually won without lend lease, but that it would have taken longer (I believe his estimate was an extra 2-3 years of fighting).

Regardless, the Soviets themselves were very cognizant of the importance of lend lease to the war effort. Stalin himself publicly stated at the 1943 Tehran Conference his belief that the Allies could never win without American production.

This previous thread should be of use to you.