It may be the lowest priority, but I think FROM is probably very happy with their PC sales.
(from
http://www.neogaf.com/forum/showthread.php?t=538569)
Looking at that picture, from April 2013, assuming I'm doing my math right,
Dark Souls PC is about 43% of the total Prepare to Die edition sales worldwide. Of course, there was no PC release for the original version, so obviously it'll make up a larger chunk of PTD edition sales, but it goes to show that it's done very well on PC for a cheap port. I'd also guess that since April, with Steam summer sale and winter sale, the PC version probably sold just as well as the console versions in the same period, and it'll continue to sell during sales due to PC games' longer tails.