Yes

No.

Have you tried http://store.steampowered.com/ ?

Nuuvem

I bought GTA5 on Steam because I'm 100% sure you can't activate keys from other sources.

reddit

"Please note that the Rockstar Activation Codes included in a new boxed version of GTAV PC or provided through Rockstar Warehouse cannot be used to add GTAV to your Steam library."

Aren't you forced to have a Rockstar Social Account to play the game? I know that I needed one for Max Payne 3.

The only way to get a Steam version of GTA V is by buying on Steam. Every other authorized sellers (so, definitely not G2A) are selling Social Club keys, unfortunately.

you could try this one. but the site is in russian. You can pay Euros or $ with webmoney or cards. http://www.plati.ru/asp/pay.asp?id_d=1915352

there are traders who sell steam copies for ~45$. just check steamgifts.com/trade and use the search function (and pick a high-rep trader!).

I got my copy of GTA V for around 23€ from a Chinese trader, but that was in January. Now it's locked.

Wait a month, buy it for half the price.

Buying directly from Steam is usually the best option. Why wouldn't you? 0% chance of getting scammed, no shady business, devs get the money to make more games, the ability to pre-load (in the case of pre-orders), etc.

curetnly best deal for it is nuuvem for 27bucks, you wont get it cheaper anywhere now

No, you can buy games at authorized retailers, like HB, GMG, GG... You can try some of unauthorized ones but as always there is risk. Also some of them offer guarantee safeguard....
But I don't know why are you hoping to get just released game for cheap... ?

The only steam version available is from steam store. Any steam gift of the game that you found is a risk. It's possible to be a real deal, maybe from a RU steam store or something like that. But i gifts are becoming a little too risky. I bought mine from retail, non-steam. Enough for me, and i am a guy who likes to have all in my steam library. But i am also a guy from ps3, that played always from rockstar social club, so.

But always be aware of steam gifts from retailers.

you can buy it on several sites for Social Club. And if you have a physical copy of the game, you have to activate it on Social Club too

Wait a month or so. There will be discounts galore. Play something else in the meantime. :-D

You could always try GameKeysNow.com for keys, but the version they're currently selling uses Rockstar instead of Steam.