Unless Russia decides to completely move off of "petrodollar"...they've already started to back RUBLE with gold and one of their largest oil suppliers, Rosneft, has moved to EURO as their default currency.
If they backed their ruble with gold, the war would be over in a week. The Russian economy is functioning (barely) because they can print as much rubles as they need to pay the soldiers and factory workers.
"Easy money, easy wars, hard money, hard wars".