Idea: Gifters be awarded points for Giveaway after Giveaway winner marks Received.

No. No one needs more incentive than they have to enter giveaways.

system is not perfect but its good,
i never run out of points for last few months ʕ•ᴥ•ʔ

Yes, especially since the new system killing the excitement in this site....

However, it should match the fact that if your game is full value, you have the full point, if bundled, half of it. If free....nothing.

There is a saying "Don't try to fix that isn't broken"

There is already a level system that awards gifters with higher chances and 6 points per 15 minutes should already be enough for giveaways unless you are a hoarder. My answer is no.

To be honest this wouldn't have any real effect since everyone already gets 6 points per 15 minutes.
The main problem with this issue is that there are very cheap giveaways (like 1 point giveaways) that you could abuse with this system.
Other than that (if they find some good solution to prevent abuse) I don't think it's a bad idea. Just consider it a small tip to people that genuinely give stuff away.