How do I repair a huge hole in leather furniture??

Not much you can do given the material its made of. Unless you have an expert come in and look at it. I imagine it would cost a small fortune though.

What do you mean by "hole?" Do you really mean a tear of some kind? What kind of leather and color is it, please? There may be some things that you could do yourself...

If the hole is not too big it may be repairable but would need a qualified technician to do this for you. If the hole is very large a replacement panel can be coloured to match your leather and then replace the damaged one.