Judging by a freshly leaked slide, Nvidia's Maxwell GPU architecture has been pushed back to 2014.
According to the slide posted over at Wccftech.com, the 20nm Maxwell GPU is pushed back to 2014, while Kepler will get a refresh in the first half of 2013. Nvidia previously planed to get Maxwell out sometime in 2013, but TSMC made a decision to go for 20nm in the Q4 2013 forcing the Maxwell to 2014.
Of course, Nvidia could have it ready in early 2014, and show it at either CES in January, or keep it for CeBIT 2014 in March.
In any case, Kepler is here to stay, and apparently, Nvidia plans a refresh sometime in 2013. According to the leak, the Kepler refresh is scheduled for the first half of the next year and everything points out to March and the 2013 Cebit show. Of course, nothing is carved in stone.
You can check out the new slide here.