It's hard to believe it but GTA V was released way back in 2013 for Xbox 360 and PlayStation 3, and now, six years later, the game is still as popular as ever, with Take-Two reporting that the game is still selling around 10 million copies a year.
At least, roughly. The figures show that in May 2018, total sales so far were 95 million units, which had expanded to 110 million units in May 2019, which equates to roughly 5 million copies in six months, or 10 million copies a year. This is pretty phenomenal for a game of this age.
In total, there's been 115 million copies of the game sold, which would theoretically also be the total reach of GTA Online's possible userbase, although it's possible many people bought copies on more than one platform.
To put this in perspective, Red Dead Redemption 2 has sold 26.5 million copies since launching in November last year on consoles, which is a full year's sales. Given GTA V has managed to sell half of that six years after launch helps demonstrate how impressive that figure is.
There's no doubt that GTA V is a cash-cow for Rockstar Games, and it remains to be seen if Red Dead Redemption 2 will match it's success, although I suspect it won't be far behind, even with it's somewhat rocky start on PC.