Fatima is a demonic apparition calling itself Mary to deceive the gullible.
The so called promises that apparition made concerning the rosary are enough to show that it was NOT from God.
This is the first I've heard of that. I know that Medjugorje has been debunked, but my understanding is that all orthodox Catholics consider Fatima a true Marian apparition. There is controversy about whether we've been allowed to know the third secret, and what it is, but the apparition itself is generally regarded as true.
There is so much dissension in the ranks of orthodox Catholics these days. There are those in the SSPX. There are those in the "New SSPX". There are those not in the SSPX who either believe the SSPX is in schism or is not in schism. There are sedevacantists. There are all sorts of views on Vatican II including that it was good, but not properly interpreted, that it was bad but still binding, that it was bad and not binding, that it is evidence that the post-conciliar church is heretical, etc.
So even being an orthodox Catholic doesn't guarantee anyone that he/she has the correct beliefs because there are so many varieties of orthodox Catholicism.
If any of the Protestant or Catholic sects are correct, then the number of saved will be in the thousands at most.