How does social-economic status affect if one survives or falls victim to the Red Death?

In short, it doesn't. This is actually one of the central messages of the story: that neither wealth nor status can protect a person from every human being's natural and necessary end—death.

Prince Prospero has a lot of money, but this does not ultimately protect him. He has the ability to remove himself and one thousand of his most healthy and interesting friends to a distant abbey, far away from where the illness rages, and this cannot protect him either. He can afford to supply the abbey with anything and everything his guests might need or want, even the stuff of fantastic dreams they've never had, but nothing can remove him—or them—from harm's way because death eventually comes for us all. Money might extend one's life, but it can never render one immune to death.