Is there a way to make toilet porcelain dirt and stain resistant?
What you would need is a product that will apply a "hydrophobic" coating to your toilet. Hydrophobic means that it will repel water, and make it very difficult for anything to stick to the surface. This would reduce the amount of effort required to keep a toilet clean.

At this point, there are not many products on the market with these properties which are available to consumers. So far I have only been able to locate one of these products.

The following is not a product endorsement. I do not have any affiliation with the manufacturer, and am only listing an example. I have also not tried this product myself, but there are videos online of this in action, and it appears to be very effective at repelling water.

http://www.rustoleum.com/product-catalog/consumer-brands/neverwet/neverwet-kit/