PUBG is the third highest earning game ever on Steam, according to Gabe Newell

At a roundtable interview at Valve's studio in Bellevue, Washington today, Valve founder Gabe Newell noted that the company created a "hole" by not shipping any new games after Dota 2 (and says they're going to start doing that again), but also took a little credit for a game Valve didn't make.
Valve's hardware and technology research has been an "investment in the future," said Newell, one which he connects to the incredible success of PUBG. "[That investment] does help do good things for the gaming industry. So you can have a relatively new game like PUBG, and because they can capitalize on all the other multiplayer games, the technology, the fact that China is now a huge market for anybody who does PC game development—So PUBG can come out of pretty much nowhere and become the third largest selling game in Steam's history. Their gross revenue over all time is already number three in fairly short order."
That's the first we're hearing of PUBG's lifetime Steam revenue compared to other games on the platform, though we'd obviously assumed it was up there. Newell didn't say which games were in the number one and two spots, though Valve's own Dota 2, Team Fortress 2, and CS:GO are certainly high on the list. Naturally, PUBG was included at the top of Valve's year-end list of the highest-earning Steam games of 2017.
Newell didn't say more about how Valve's non-game development efforts helped PUBG come along and earn its top three spot, though as it released on Steam and is the most-played game on the platform by far, Valve's huge userbase and Steamworks API were obviously factors. We can only speculate as to how PUBG might of fared in a world without CS:GO and without Steam.
Newell wasn't just patting Valve on the back. He noted that the company's focus on technology and hardware (such as the Steam Controller and SteamVR sensors) and "investment in being worried about where the gaming industry is going" has meant that it hasn't been shipping games. That is set to change, with multiple new Valve games planned.
Of those new games, the only one we have details on is the recently-announced Dota 2 card game Artifact. Incidentally, that was the reason for our visit to Valve HQ this week, and we'll have more on it from Tim soon.