Jiraiya wins if he starts out in sage mode, and he knows how to handle Amaterasu since he probably figured something out about it and it is also shown you can run away from it. Plus jiraiya can avoid Susano'o with his reverse summon, to summon himself into a toad somewhere else. Jiraiya surpassed Sasuke in many things and we have'nt seen sasuke's EMS abilities.
Sasuke dodged Itachi's Amaterasu in his normal form with his regular speed, so why should Jiraiya not be able to?
For now i have to say Jiraiya will win with High diff, yet sasuke will surpass him. (Soon)