Today I released the widely required Setup.App Patch for iPhone 5S for both variants. This Setup.App is compatible with iOS 9.3.4 build released by Apple to patch Pangu's x64 Jailbreak.
In order to create the CFW, you can follow the video for iPhone 5 I posted in the description, it is still up to date. As a base software, use iPhone 5,1 iOS 9.2.1 for 6,1 and 5,2 iOS 9.2.1 for 6,2.
In order to attempt restoring, you will need an updated version of LibiMobileDevice that IS compatible with x64 devices so that you won't get FDR-related errors after starting the process.
The updated version can be found here, in the video description or in the video I released yesterday. There is also an OS X version released.
Please make sure you download the correct IPSWs corresponding to your iPhone 5S version (6,1 or 6,2).
The patch: https://mega.nz/#!l1FUjA4J!lhPRoU4rca0Q7RXbKL1buGgHJ72XUif8x7h9eBy2PbQ
CFW Creation Tutorial: https://www.youtube.com/watch?v=tFcsC9kGKQQ
Updated LibiMobiledevice: https://www.youtube.com/watch?v=9bObMycOZtI
Firmware Manager: https://www.theiphonewiki.com/wiki/F.C.E._365_Firmware_Manager