How to block a game to appear on SG?

There is a symbol in front of the name of the game giveaway (:

Its an eye with a slash. Click on it

Yes. Next time you see a giveaway for the game, click on the little grey crossed-out eye icon next to the game's title.
(on the list page, not the giveaway's individual page)

You can. I dont remember how.

TL;DR:
Its possible.

Yes.

When you see the GAs list, and spot the name of the game you want to blakclist, you will see 2 icons on the right of its name. First one is the steam page, second one looks like some kind of eye. When you click on it it will blacklist the GAs for this game.

click on the eye icon to hide, you can only do this from the homepage.

you can check your hidden games here

View attached image.

ty all