one word:anime
Madara said that blue steam wouldn't be enough, that he'll have to use red steam to make any difference.
He was tempting Gai to use 8 gates
Good eye. I'd also like to ad that when Guy does a technique like asakujaku or hidora, he's attacking with speed and power beyond what he normally can in the gates, which demonstrated that if Madara could intercept hidora, he could without question, beat Guy in speed and strength.
Despite this, it's still incredible that Guy's capable of keeping up with Madara to the extent he's doing.
Even 8th gate gai wont be enough to defeat Madara