It's funny, I heard of people either getting a TON of sales from changing their tags to Black Friday Etsy or getting no sales from it. I personally didn't get any sales but i did get a couple of views. But I am not going to make an opinion about how helpful something is based off only my experience with something one time. There were still a lot of people those tags worked for, even if I wasn't one of them.
That being said, if you start typing Valentine's into the search box you will start to see a bunch of suggestions appear. Like Valentine, Valentine Card, Valentine Decorations.
I wouldn't do just Valentines Day Gift because that is in the same realm as "Stocking Stuffer;" it is a vague tag that could be used to describe nearly anything. And really, let's face it. Who here found a gift for someone this Christmas by typing "Christmas gift" into the search box?
People will type in things like "Valentine Card," "Jewelry," Heart Jewelry," "Heart Candy" etc. It is a waste to be too vague with your tags. Definitely use the word Heart to describe any heart shaped items you have though!