America has its 2021 population in WW2. How quickly can the Axis be defeated?

Suppose the United States had the same number of people in 1941 as in 2021. This includes the infrastructure and industry to support the 331 million people. The butterfly net is lifted after Japan attacks Pearl Harbor. How quickly could the Axis be defeated in this scenario?

This is just 1941 America having 331 million people and supporting infrastructure. Not the 2021 US population being sent back to 1941 or anything like that.