Microsoft Corporation has sold under 1.5 million Surface tablets according to Bloomberg. This number includes around 1 million Surface RT tablets and about 400,000 Surface Pro tablets. The Surface RT was released in October 2012 and the Surface Pro was released in January 2013. The 1.5 million figure is a small dent compared to the number of tablets that have been sold running on Android and iOS.
Apple sold 23 million iPads this past holiday quarter alone. Tablets that use Android built by Amazon, Samsung, Asus, and Sony control the rest of the market.
The sales of Windows 8 software itself is doing very well though. Microsoft has sold around 60 million Windows 8 licenses so far to manufacturers. This does not reflect the number of consumers that have picked up a PC powered by Windows though.