When will the 6d mk ii be added?

As you are posting in the Sierra community we assume you are using Sierra, Camera RAW support in Sierra has not been updated since 19th July 2017.

See the list here, Digital camera RAW formats supported by iOS 10 and macOS Sierra - Apple Support

Here is the list for cameras supported in High Sierra, Digital camera RAW formats supported by iOS 11 and macOS High Sierra - Apple Support where the Canon 6D MKII makes an appearance.

So you will need to upgrade your OS to High Sierra if you want to see your 6D MKII's images in Photos, Preview or Finder.

Otherwise use Canons own software, or download something like Adobes DNG converter which is free,

Adobe - Adobe Camera Raw and DNG Converter : For Macintosh : Adobe DNG Converter 10.3

Ask Canon tech support. It will only be supported if Canon releases a version of their driver that supports it on the Mac. Apple does not make printer drivers.

If you decide to upgrade, check to make sure your applications are compatible.

Application Compatibility

Also check to make sure there is a compatible driver for your printer.

Do a backup before installing, preferable 2 backups on 2 different drives.

How to get macOS High Sierra