Anyone with a heavy duty machine should be able to stitch in a patch of cordura, ideally a couple of layers. If you live near anywhere anyone sails, then there should be a sailmaker who can do it, similarly, parachute/hot air balloons, or even custom upholstery makers. You could also get some cordura yourself and hand stitch it, because the weave is pretty loose, it's not super difficult, just need a good thimble or a bit of leather to press the needle (bigger would be better in this case) If you do ask someone to do the work with a machine, make sure the tent is really clean, as any grit or dirt is really hard on sewing machines. You can also use wide webbing, but a wider patch will let you distribute the force more and reinforce the rest of that corner.