Chip vendors like Qualcomm, Nvidia and Broadcom will be ready to sell their 64-bit quad core CPUs by the first half of 2014. A quote from sources states:

"The planned 64-bit quad-core smartphone chips are expected to debut at CES 2014 at earliest"

MediaTek have orders for a 8-core CPUs, as we saw in this article, by many China-based smartphone vendors but other smartphone brands have their concern about those kinds of chips. They are seeing bigger competition in the face of the 64-bit A7 chip in the iPhone 5s. The sources also added that:

"To cope with demand from smartphone vendors, Qualcomm, Nvidia and Broadcom reportedly have revamped their product roadmaps for 2014, aiming to release 64-bit smartphone solutions in the first half of 2014"

MediaTek may delay the launch of its 64-bit CPUs to the second half of 2014.

Source