Many Orthodox priests were martyred, true. May they pray for all of us.
On the other hand, some "Orthodox" bishops and patriarchs drew their salary from the KGB.
Also on the other hand, the Catholic Church within the ex-USSR was virtually exterminated. We lost thousands of priests just in Spain, just due to the communist revolution supported there by Stalin.
As an aside, concerning Fatima. The Orthodox get very excited because they assume "Russia will be converted" means "Russia will become Catholic". However, the visionary Sr. Lucia indicates that "the conversion of Russia" may have already taken place. It seems that "the conversion of Russia" really meant her "conversion" (i.e., "turning away") from communism, rather than her "conversion to Catholicism" or even her "re-conversion to Orthodoxy".