It all depends on how the fight starts tbh. Assuming the fight takes place in a neutral universe and under equalization rules, if Thanos gets caught in Itachi or Madara's Tsukuyomi before he does an omniblast/tries to mindrape everyone, he will lose imo.
Plus, Sage of Six Paths is ridiculously powerful if he's being used here. He created the moon out of the earth on his death bed.