First, let me say that I thought determination increased your healing received. That's how I read the tooltip.
Silly silly easy test concludes that determination effects your healing output, or nothing at all (bugged).
Physick'd myself 5 times for an average of 800 with 259 determination.
Physick'd a level 10 bard 5 times for an average of 795 and he had 25 determination.
I know that someone will come back and say that 5 barely even counts as a sample size, but the second target had 10% of the determination I did. I'd say that's sufficient enough.
Now, had the cure been for much less, I actually wouldn't be posting this because I would have thought maybe there was a target's-level penalty in the cure formula.