This is enough proof to show that piracy IS hurting PC game sales a lot:
-Super Street Fighter 4 Canceled on PC due to Piracy (and now Capcom is giving a second chance)
http://www.1up.com/news/super-street-fighter-4-canceled
-Crytek swears off PC-exclusive games due to piracy
http://arstechnica.com/civis/viewtopic.php?f=43&t=1087435
-EndWar PC version coming after console version due to piracy; PC pirates would cannibalize consoles sales (and Ubisoft did it with Assassin's Creed and other games)
http://www.shacknews.com/article/55166/endwar-pc-coming-after-consoles
-Ubisoft CEO changing focus to consoles due to PC piracy
http://www.tomshardware.co.uk/ubisoft-guillemot-E3-games-piracy,news-28947.html
-Epic Games: Piracy has killed our enthisiasm for PC
http://forums.computerandvideogames.com/viewtopic.php?p=1690755&sid=4545b70e0d95da8c9de4dcf61867bbc1
I can give you MUCH more, but I won't spend more of my time in this thread (but yes, I am happy to see that SSFIV:AE is coming for PC, so I will be able to play it with some friends). We all know it's a fact that piracy is a big (really big) problem in the PC gaming industry, so there is no need to argue against facts.