If you are saying raw damage yes Psi will prevail but Mage sacrifices too little damage for the safety it has. Psi has all the damage but Mage's damage is close to psi with way more safety. At least when I was playing the game it was a fact.
Psi can break all beams on Zalesky Posad's last boss using twin + Astral form damage reduction stacking, or take up to 3 green orbs spawning in a row on Plague city first boss.
Those can be taken without any loss of dps as there's still spare talents after taking everything essential. Rubies are completely different story though...
I've done that on P2P where there's no patronage 5, so everyone takes damage greater by at least 50 percentage points. Not sure if mage can top that.