They may have the resources, but getting them where they're needed can be a challenge. Russia has demonstrated multiple times it's lacking in terms of logistics capabilities, but I think it could happen to any country, even the best organized.

That, and they might be selling the oil and gas abroad to finance the war.

These are just conjectures. I don't have any proof.

That's the problem with an economy that depends on energy exports when you're being sanctioned and have a war to fund.

Apparently it was a 60 year old guy and there was a power outage for days. Old people tend to die when they are not in their ideal environment. Even young people are known to die when exposed to cold temperatures. If you are an alcoholist to boot, which many russans stereotypically are portrayed as, you stand even less of a chance.

Not sure what exactly caused the outage in the specific region the referenced dead guy was in. There has been outages in and around Moscow, Saint Petersburg, Leningrad Oblast and Omsk recently. One power outage in Moscow was caused by a failure in their centralized heating infrastructure, a "burst heating main" in an ammunition factory. I assume it was hot water or steam pipes. A preliminary investigation cited “improper operation of the boiler room” as the cause of the burst pipe and resulting outage. This caused interconnected industrial and residential areas to not get their heating delivered for several days. I assume people without heating turn to electrical heating as a substitute and end up overload the grid, causing electrical outages as well. There is also some poor management of the grid. Transmission lines being disconnected cause of snow when they are needed the most etc. You know, the usual.

Those who can are of course turning to running gas stoves etc.

Oil gets too viscose if it gets too cold. It turns into syrup. The other thing is that city central heating is a great system, if it is well maintained. If you lack the ressources and oversight and the system fails it is difficult to get back on track. Worst risk is the pipes in the houses or to the houses freezing. The expanding water will burst them and you need to redo the whole piping. Normally for ground laid pipes in moderate climates it os not an issues as they are laid below the level until which the ground may freezes. But god knows if that was done properly and how deep that needs to be in Siberia.