The ruble isn't backed by gold. You can buy rubles from the Russian government with gold but that's not backing; backing would be if the Russian government would let you exchange your paper rubles fr gold when you ask and they aren't doing that.

So why would anyone want to trade their gold for paper rubles? Russia is requiring that their exports (mostly oil, to countries not participating in the sanctions) be paid for in rubles. So what's really going on with the ruble and gold is that Russia has found a way of getting the rest of the world the prop up the ruble.