how can I get access to NAS through apple tv

no

with the new model coming up that has apps maybe

if you have an ios device that does have apps for the nas like my synology nas has for ios then you can airplay stuff to the appletv

You can't. There is no provision for accessing NAS drives from an Apple Tv directly.

If you have a Mac you could access the NAS from the Mac,and then Airplay to the Apple Tv.