Can you fix an above ground pool that has hole in the side wall?

Yes, you can even if the wall is rusted out you can patch the wall by using a scrap piece of wall available from a pool shop cutting it so the the patch covers the hole at least 100mm all round then secure to the wall with stainless pop rivets (remember rivet from the inside) silicone around the patch so there are no sharp edges,replace the liner and your back in business.