Officially, Belgorod is estimated to be 75% complete. It has the complete hull, launchers, reactor installed, the works. However, unofficial news have been neither here, nor there.
What is almost 100% certain is that it will never sail according to original design (it's main arsenal, Granit missiles are no longer in production).
Great pics.
Yes, it is not being used as an SSGN, but I am pretty sure that is was launched and commissioned. As I understood it, it got a special fit out to be used for special missions.
As it is, the Russian Navy has four Oscars that are active and in service, and another two either waiting for, or in overhaul.
Northern Fleet:
K119 Voronezh, active and in service, completed overhaul in 2011
K410 Smolensk, active and in service,completed overhaul in 2013
K266 Orel, inactive, in overhaul. Caught fire in April 2015.
Pacific Fleet:
K186 Omsk, active and in service,completed overhaul in 2008
K456 Vilyuchinsk, active and in service.
K442 Chelyabinsk, inactive, awaiting overhaul.
There are two others that were never completed and are still there:
K-135 Volgograd, incomplete, construction restarted
K-165 Barnaul, incomplete, never launched