From Software executive director Eiichi Nakajima has announced that Dark Souls has sold 2,367,000 copies. The original release sold 1,675,000 units while the Artorias of the Abyss Edition made up the additional 692,000 units.
The PC version of the Artorias of the Abyss Edition was the most popular; the PC release came later than the console versions and was also the first version to feature the extra content on the disc. Nakajima also added that that Dark Souls II will release on Xbox 360 in Japan, whereas Dark Souls never did.
To find out more about Dark Souls II watch this brutal gameplay demonstration.
Source: Destructoid.com