North Korea has even bigger army. And they rely on soviet era stuff too.
According to statistics Russia has estimated 13000 MBT's of which only est 750 are from the 90's (the T90), the rest are soviet era old stocks (mostly combination of T80 and T72's). Same applies to just about everything. They are spending a lot of money on military and the size is huge, but they are no miracle workers.
Looking at all those social media videos of trains moving troops it catches eye how much eg 1960's legacy ZIL trucks and other soviet era hardware there are.