The more research i have done about the subject, the gathering of the 144000 in revelation it is a reference to a military census done in the book of numbers before the Jewish people moved into the promised land and the great crowd is a reference to this new multi ethic family of both jew and gentile called the body of Christ.
It's really just the theme of the new testament. Old conevant to new constant, Jewish people to body of Christ etc etc.
The 144 is most likely just a symbol for the body of Christ or church.
Of course it's all very subjective like all propheic writings