Source: http://www.engadget.com/2013/10/30/valve-steam-65-million-users/
Valve's Steam service for PC distribution and sales has over 65 million users playing its over 3,000 games, the company announced this afternoon. That's a 30 percent increase (15 million accounts) over the last 12 months -- not too shabby! -- putting the service's userbase well above that of Microsoft's Xbox Live (which has 48 million, according to MS). Not quite the 110 million that belong to Sony's PlayStation Network, but not too shabby.
The new Steam number comes ahead of Valve's planned hardware beta, which intends to test the three main components of the company's big living room push: SteamOS, Steam Controller, and Steam Machines. The first of those components, SteamOS, is a Linux-based navigation solution for gaming PCs in the living room. While in can be installed on any PC (and it's free), it'll come installed on the physical Steam Machines that Valve ships to 300 beta participants (alongside the aforementioned Steam Controller). That said, at 65 million users, you have 0.0005 percent chance of being chosen for the beta. Best of luck with that!