8th Gate Gai's powers are limited. The only person he will kill is himself.
A win for Guy is to completely kill Sasuke before his 8th Gate runs out. It's
NOT a draw, lel. Hashirama defeated Madara first then he won. People are just jealous that 8th Guy is too OP. Imagine Hashirama did died in the battle against Madara, but end up dying as well, so it means Hashirama won the fight. Winning the fight and die of a match is completely different. Guy takes the first kill, then he wins, or Sasuke takes the first kill, then he wins.
BTW, Naruto and Sasuke's final fight managed to end both of them, but in the end Naruto won the fight by Sasuke's own words. You have to understand that Guy's 8th Gate can almost kill anybody below Juubi Jinchuriki Level.