I'm no expert, but here's my take on the situation.
We all agree that turbos are powered by exhaust gas. So the question is
Where does the exhaust gas come from?
It is the product of fuel combustion and is expelled during the exhaust stroke of the engine. Therfore we can make the following cases:
1)More fuel => definately more exhaust gas.
2)More rpm => more revolutions (cycles) per minute (fuel injected every cycle) => more fuel per minute => so we're back to #1
So yes, both statements are true, but rpm is an indirect relationship for the turbo, where it is a direct relationship for the S/C.
