"heat input" as defined with the variables of volts, amps, and travel speed. So according to the definition, no, changing the gas does not change "heat input".
Now according to the arc physics, the plasma temperature will be higher, which combined with some other things typically makes the material flow better. I've welded some materials where helium additions didn't make a whole lot of difference, I've welded other materials where you needed every bit of helium you could get. It all depends.
I'd suggest trying it just to say you've run it, but try it on something you don't care about before you try it on something that counts. DCEN helium on aluminum is an entirely different animal than AC aluminum. Oh, and prep, as Lawrence mentioned above, is everything.