If the clutch of a V8 was slipping buddy, and you kept your foot down, there would be a bad smell, lots of smoke, and a red hot ruined flywheel.
How anyone can fail to realise a clutch is slipping is beyond imagination.
If you let the clutch right up, then deck the gas pedal, and then the engine speeds up but the car doesn't, the clutch is slipping.
There's a solution - fit a new clutch.
CharlesY