Hate to have to tell you that it's no doubt permanently etched. That's what acid does to marble. Keep the Kaboom far away from your marble counter and use glass trays for placing perfumes etc. Use only water or a pH neutral cleaner like Shaklee's Basic-H2 for cleaning any natural stone.

I guess there is no way of knowing how deep the stain goes? You could check with a local stone installation store and see if they could sand it down, perhaps.

When I have gotten oil stains on my granite, I applied a home-made made poultice which pulled the oil out. But as carolpolki writes, Kaboon is acidic, so that's a different problem.

graywings,
How do you make a poultice?