You can't sign up for a Grand Theft Auto 5 beta; nothing has ever even been mentioned about a Grand Theft Auto 5 beta. Heck, it's unlikely Rockstar will even do a beta for GTA5.
That's why when you see any website or Facebook page saying otherwise, you know it's a scam. And there are plenty of them.
Take-Two has been busy legally shutting them down, having won victories in February this year against getgtavbeta.com and betagtav.com, reported Fusible.
Take-Two filed two more complaints this week against gta5betacode.com and grandtheftauto5beta.com, taking its number of open cases - relative to these scams - to four.
The websites lure you in then make you share-spread the scam with your friends on Facebook. Only then are you allowed to download a file onto your computer. A file. I don't know what that file is, but the dangers of downloading unknown files - and possibly even executing/running them - are many.
Don't fall for it!
Grand Theft Auto 5 is out in September.