A reasonable answer, IMO, would be somewhere between 0.5% and 5%. The average CEO gets maybe 1%, which I think is pretty fair.
Often if a CEO makes 1000x an employee, it's because there are tens or hundreds of thousands of employees under them. The executives still get a relatively small portion of employee output.
I must say though that being more valuable than 1000 employees seems like a very low bar to me. I'm sure there are many people who are more valuable than even 100,000 employees.