If he didn't come from a breeder with pedigree papers you can't get pedigree papers. Breeding of cats is a newer human habit and most breeds are based on naturally occurring traits. Even the best lookalike may have no blood relation to a breed and DNA testing for cats heritage is far from acceptable for verifying pedigree. Therefore, the only way to determine if a cat is a breed is to have documented lineage for several generations.
Kieka’s response is spot-on. The only way to get a cat with pedigree papers is to get one from a breeder. The cat DNA tests that are available now (UC Davis and Basepaws), look at which breeds have the highest degree of genetic similarity to the cat being tested. So, while the test may come back with Russian Blue being the closest match for your kitty, it won’t definitively prove that he is a Russian Blue.