There is no official data, yet, regarding the units sold neither for Oculus Rift nor for HTC Vive, Steam data suggests that the Vive headset sales are approaching the 100K mark. While theSteam Hardware & Software Survey is a good source to see the percentages of hmd used by their users it is not a very accurate measurement of the sales figures.
So if we consider another important factor, games that come bundled with an HTC Vive sale, we can say that those particular sales would reflect an accurate number of Vive units sold. SteamSpy collects data from millions of Steam users and turns it in ll sorts of statistics about games sold on the platform. So judging from the three VR games that come bundled with each Vive purchase: Tilt Brush, Fantastic Contraption, and Job Simulator we can see how many owners are there.
Tilt Brush is the most popular of the Vive’s bundled games, with 94,911 owners with Job Simulator at the other end coming in at only 73,137 registered owners. One hypothesis for this gap is the name of the game itself: users are missing the humor of the game’s name and not downloading it.
We need to consider that some people might purchased a Vive through a local store and don’t know they can get the free bundled games. Others may have bought the games for VR just because of the summer sales, but did not yet get the Vive (at 800$, maybe they’re still saving for it), so please take these numbers with a grain of salt.