According to data from Valve's Steam Hardware and Software Survey for the month ending January 2014, Microsoft's latest operating system usage has increased to a combined total of 21.31% for both Windows 8 and Windows 8.1. During the previous month, the usage was at a total of 20.06%. 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 this data, Windows 8 32bit has a share of 0.55%, which is a 0.03% drop compared to the previous month. Windows 8 64bit had a share of 10.01%, which is a 0.55% drop compared to the previous month.
On the other hand, Windows 8.1 32bit saw a 0.04% share increase to 0.34%. Windows 8.1 64bit, being the most popular, saw a 1.88% share increase to 10.41%. Windows 7 64bit holds the trophy as the most popular Windows operating system for those who use Steam, having a 50.56% share.
NetApplications also released their market share data today, indicating that Windows 8 and Windows 8.1 have a combined market share of 10.58%.