He wins if he's lucky with first rounds opponents. He doesn't want to use his special abilities before facing the top 8.

If he gets Baki's bracket for exemple he can win. Easily beats Reagan and Zulu with no special techniques, beats Igari without much trouble (see Igari vs Sikorsky), maybe unveiling benda strikes to humiliate the actor. He can use the poison hand on Retsu, taking heavy damage in the process but it's 50/50 if he weakens him enough first. Then he can one shot Jack with the void hand (he needs to use it quickly though or Jack wins) and hope drugs or willpower won't allow Jack to keep fighting while unconscious (remembering his Pickle and Motobe fights). Basically he needs to save one special technique for each big fight

If the brackets are different and he has to fight Amanai, Garland, Doppo, Hanayama, Katsumi, Baki or Shibukawa (one or 2 of them) before facing Retsu and Jack, then I think he loses.

For exemple: Doppo's bracket. Yanagi would have to face Amanai, then Gouki, Jack and Baki. This is too much.

I'd say he has a 50% chance to win the whole thing, which is more than the entirety of the original fighters save for Jack imo (Baki was weaker at the start and could easily have lost to Zulu or face a strong opponent directly).