Did Jewish prophecy foretell the loss of 6 million specifically?

No, not specifically. Ezekiel 37:1-8 describes a dead "nation" coming back to life, however. After WWII, the Jews lost and out of their homeland began to slowly return, and in may of 1948, the Nation State of Israel was declared as an independent country. They were recognized internationally by the League of Nations, the precursor to the United Nations.

I haven't heard of anything like that.

The Torah is the blueprint of the world. The Torah says there are a certain number of animals that chew their cud and do not have split hooves, so there are only that many in the world. The Holocaust was also written into the Torah. If one was a great enough scholar you could see where the Torah says 6M.

A person can battle the systematic extermination of Jews using the rosary and fasting.

That sounds ridiculous- someone foretelling that 6 million people would die.

Even if they did then they got it confused with the $6 million dollar man .

 Tyre is still around so there you have it - Pure prophecy stupidity