Viewing/Searching for Old comments

No, comment history isn't an official feature of Steamgifts.
However, Revilheart's ESGST userscript allows such a feature, to a certain extent.

Only SteamTrades has that feature at the moment. ESGST has a feature that keeps track of your comments, but it can't show you comments you made before using the script. If you remember words that you used in the comment you can try googling.

Restricting Google to SteamGifts is the best way I've found to search for a specific user's comments.
Something like site:steamgifts.com "Arcsurvivor" or site:steamgifts.com/discussion "Arcsurvivor"

I was actually looking for a comment I made on a giveaway. Can I actually find it?

I wouldn't mind seeing this added to SG.

Besides esgst and Google 's specific search by web search,
If you can remember the topic, maybe you could search your internet history if you still have it and sort through it?
This is probably a last resort option though, only use it if you absolutely need to find the comment.