Seems like a fire support vehicle based on the Kurganets chassis and armed with a 125 mm gun. Very nice.
The large calibre support weapons which look like a grenade launcher and a light cannon suggest to me it is a BMPT type fire support vehicle.
The gun has the bore evacuator in the wrong place to be a 125mm gun... it might be a 120mm gun/mortar that might be able to fire missiles, but would primarily be direct fire HE.
As it is a naval infantry vehicle it might be what they want instead of a MBT for landing on beaches.... a direct fire HE round and cannon/grenade launcher capacity that acts like a tank but in places where the enemy does not have a lot of tanks... or enemy tanks will be emplaced like fixed guns and therefore could be taken out with missiles at extended ranges.
I would think an actual MBT version of Kurganets would simply have the T-14s turret fitted to it because it already has the gun and ammo and sensors and equipment needed to be a tank... and wont be particularly heavy as it wont have heavy armour.