Not exactly Kunal, situation in Russia is a bit complicated.
The T-80B/BV, T-80U and T-80UD are still in service in Russian Army. These will be used untill all spare parts will be used.
T-72B/B1 and T-90/T-90A are used as a basic tanks in inventory, simply because it's manufacturer, UVZ is the only one left in Russia.
Older tanks, like T-64, T-62 and T-54/55 are still used here and there, but are slowly decommissioned.
However because on Ukrainian, KMDB and Malyshev factory, where T-64 series, T-80UD and T-84 series were developed, is still functioning, this is why Ukrainian armed forces as basic tank use T-64B/BV and upgrade them to T-64BM Bulat and see as a promising tank T-84M Oplot.