The break is very close to the tube, so IMO welding is probably out. But it is repairable by brazing. Any decent torchmak should be able o do this for you at low cost if you don't mind burnt paint and some down and dirty repaint of the rear triangle. A nicer job would b to replace the dropout, but that's a bit more complicated since it loses the positioning.
BTW- just guessing by the photo, but I wonder if the rear triangle width was not matched to the hub. If so, you need to correct that before brazing, or it'll just break again.
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