Can I make a living on ebay?

It's very possible, most of my stores are in the clothing niche though, where eb+pp fees sit at 15.4% before discounts, that's a very large number so do bear that in mind.

You can make $1,500 in a single day on Ebay!

Depending on how many accounts you have what your selling and the magnitude your selling at.

Do some research before selling. See for how much others have sold your item: enter the name of your item in ebay search. Click "buy it now" and when check sold or completed listings. Do the same with auctions.
You can test if your item will sell without having a product. Make an auction for 5 days (make start time in the evening when most people are at home) and bid from other account the amount that no one would overbid. Do this several times and you will have an idea...