According to data from Valve's Steam Hardware and Software Survey for the month ending June 2014, Microsoft's latest operating system usage has increased to a combined total of 25.11% (up from the previous month's 24.98%) for both Windows 8 and Windows 8.1. This factors in both 32bit and 64bit of Windows 8 and Windows 8.1.
This data is collected by Valve's Steam game client, for those that did not know, and measures hardware and software stats on a monthly basis. This data indicates how much share an operating system has (among other stats) when it comes to gaming via Steam.
According to the data, Windows 8.1 64bit account for 16.19%, with an increase of 0.85% from the previous month. Windows 8.1 32bit went up by 0.04% to 0.45%. Windows 8 64bit saw a decrease by 0.46%, resting at a 8.01% share. Windows 8 32bit held a 0.46% share. Overall, Windows 8 and Windows 8.1 accounted for a combined total of 25.11%.
Windows 7 64bit remains the top operating system at a 49.41% share, which actually fell 1.12% compared to the previous month. Windows in general accounts for 95.04% of the operating system share, according to the survey. Apple's OSX has a 3.59% share, while Linux has a 1.20% share.
Windows 8.1 64bit continues its upward trend amongst gamers, albeit slowly. As the months go by, we are beginning to see a slight decrease in Windows 7 usage and an increase in Windows 8.x usage. Take these stats for what they are worth, as they do not clearly indicate what percentage of Windows users are actually Steam users.