The PS4 is outselling the Xbox One by two units to one at GameStop, a GameStop representative told GameZone. This was according to a local retailer who didn't specify whether this was chain wide or just at the individual store; however, I think we can presume, given what we already know about the two systems' sales, that the PS4 is outselling the Xbox One overall. Whether it's at a rate of two to one everywhere is still a bit of a mystery.
http://www.gamezone.com/news/2013/06/17/ps4-pre-orders-doubling-xbox-one-at-gamestop
It is not clear if the guy means a specific store or all the GameStop.
Edit - Some GAFers that works at GameStop in US are saying 2:1 and 3:1 in most of cases...
http://www.neogaf.com/forum/showthread.php?t=582581