I don't think that is true. I believe oil is a higher percentage of Saudi's total income than it is of Russia. Russia sells far more Natural Gas than Saudi.
You can’t just look at the amount of oil revenue, you have to consider the cost of extraction. The Saudis can pump oil at a cost of $10 a barrel. At $75, they’re still making $65 on each barrel.
Things are far different in Russia, where they have to drill deep wells in horrifying climates. The corruption and payoffs required add to the costs.