Only Sony knows for sure when PS4 will be released. So far all Sony is saying is "Holiday 2013" for PS4 release. PS2 was released October 26, 2000 (in North America) and PS3 was released November 11, 2006, so maybe October maybe November for PS4 release. But past perfomance is not a true indication of future results.
November 2013. WIth the way Sony has been performing with this console, they are not going to want to let the momentum run down. Microsoft is releasing the XB1 in November, so it's only logical the PS4 will release the same month, if not the same week.