Your vehicle is too new for such problems. Can't you get this done under warranty? Equinox has minimum 3 years or 36,000 miles warranty, and optional extended warranty for 5 years and 60,000 miles.
About the gauge problem, I don't see how a faulty fuel tank level sensor can drain the battery. However, you can check if there is parasitic draw by connecting an amp meter or multimeter to the battery after turning off the engine. I highly doubt your problem is due to parasitic draw, as you mentioned the jump start did not work.