Ive never heard of Olive oil to treat impaction, but mineral oil is used in many cases. I would suggest taking your gecko off the substrate (and IMO never putting it back on crushed walnut again), and housing him on paper towel at least until he is fixed (papertowel is by far the best substrate for leopard geckos IMO, easy clean, monitor feces easily, cannot lead to impaction - leos are infamous for eating substrate). As for the gatorade/water part, that has nothing to due with nutrients, all it contains is trace minerals (well, pretty much just salt and sugar) that help with dehydration. Now I have heard of people makin a sort of "slurry" for leos with banana and mineral oil (and some sort of other fruit I believe too), but it doesnt come to mind right now.
It doesnt sound like a bad plan, but I would recommend replacing the Olive oil with mineral oil. And also maybe the gatorade with Pedialyte (no dyes and crappy additives). If it doesnt clear up soon you should get him to a vet for treatment, dont let it go too long or it may be too late