I’d just dig a 12”x12” or larger trench around that thing, add some rebar or at least wire mesh and just pour in concrete. Maybe go 18-24”on the side away from the gate if the earth is a bit soft, it will act as a counterweight.

When it’s dug out you may be able to pull it straight. Get a nice chain hoist or some 10,000lb ratchet straps and give it a anchor point 15-20’ away, pull the top back straight.

If you get it stable but not perfectly level, you can always hire a welder to fix the hinge one last time.

No way that fix is gonna cost you $14k.