Yes, the book of Revelation points to the “great crowd” as representing all those persons who are not of the heavenly “bride” class, or sealed
ones, but who stand approved at the time of the “great tribulation” and are preserved alive on earth.
I think the great crowd under the alter isn't just those who die in the End of Days for their faith, but it's everyone who has ever died for their
faith. It takes a special kind of resolve to do that.