The alliance will lose only when Luffy lose
Oda always make Luffy carry the burden of either winning or losing, that's his idea of what role the captain or leader play in a war
He's even doing this with the beast pirates, Oda is showing similarities between Luffy and SHs and also Kaido and beast pirates with King and Zoro as the best example
Time and Time again Oda focused on this arc on how the alliance moral depands on how well Luffy is doing, Kaido stated that if he simply showed his head to his allies the war would be over, but their confidence in Luffy pushed them to do well against their opponents
another interesting tidbit is Luffy dialogue, Luffy declared several times he won't die to Kaido, saying no matter the number of tries, if he doesn't die he will always have the chance to take him down
this idea was pushed further by two important scenes, when Kaido knocked Luffy out the first and second time, Kaido stated that even when unconscious Luffy is still staring at him, so making Luffy lose consciousness is not enough, "Kaido must kill him"
this is the story of the fight and this war as a whole, the captains will decide the fate of the war, let's wait and see