Elon Musk:
If you have a humanoid robot that is extremely productive and can work 24/7, it works 168 hours a week.
You can expect roughly five times more productivity per week than a human.
Take the population of the United States. Perhaps around 120 million people in America have a net positive output of goods and services.
Well, I'd guess you'd need about 20 to 30 million robots to match the United States' output of goods and services.