Russia has an "official" central bank interest rate of 20% with parts of the real economy seizing up due to the country's resources being funneled into creating vehicles that last for a few months before being blown up in their invasion.
Large countries have a lot of levers they can pull to keep their economies going when they really need to, but they are damaging in the long run and get more damaging the longer they rely on them. Russia doesnt have some magical property of being extra resilient based on slavic tolerance of suffering.
How long they can do it for is a significant open question, the Russian economy is already showing serious warning signs and most of the forcasts that I've seen show 2026 as the year where things start to become very bad for them. It's not an all or nothing thing either, its not that it is about to implode and all of a sudden Russia cant do anything, but that the economy degrades to the point where it becomes difficult for them to maintain funnelling sufficient resources into their invasion.