I've looked at the gift angle. Unfortunately, it doesn't look good. (This is not an endorsement of the logic.)

There are some technical issues. The main one is that when you vote for someone, you are only flagging someone as having value for a future Steem Power divestment. The Steem Power you are trying to claim is a "gift" doesn't exist yet. You can't give something you don't have legal title to, and you can't have title to something that exists.

Second, you don't directly give the party the rewards. The blockchain does, and since you aren't the blockchain, that does create a technical problem in claiming it as a gift.

Further, the fact that you had to participate to create the rewards generally makes the IRS more likely to want to call it income of some kind rather than a gift. Just a guess, since there's no case on Steem yet.

I continue to look into the gift tax exemption for an option.