But I remember hearing in freshman religion that in Hebrew numerology, the number twelve was like a "perfect" number. i.e.12 apostles, 12 tribes of Israel.
Also, in Hebrew, the number 1000 represented a "very, great number/amount." I am not a Jehovahs Witness, and I'm not disputing anyone's religion, but I think the majority of the bible is symbolic.

This would make perfect sense then in Revelations.
12,000 from the 12 tribes wold make it. That means that a "very great number" of "perfect" or at least very good, people will get to heaven.

Steve