How is Gai finding Zabuza on the mist? He doesn't have sharingan like kakashi, and Kakashi with sharingan could barely react to Zabuza's atacks, not to mention he even got outsmarted and speedblitzed, and had to be saved by naruto and Sasuke.
Zabuza with his water clone feints was able to outsmart Kakashi, Gai is lost there.
Sharingan was the key for kakashi's victory, since it allowed him to react to Zabuza's atacks and not getting a fatal wound (tough he barely could). Zabuza is a tough one to find, and its hard to react to his silent atacks. Gai doesn't have sharingan, and his reaction speed is < Kakashi's. He also doesn't have any means to stop Zabuza's clone feints and jutsus like water bortex.
If neji's byakugan isn't there for locating Zabuza inside the mist then team Gai is screwed. If gai and lee use gates to disperse the mist then Zabuza adds more ore just uses v2 mist, that was so thick it completely blocked Kakashi's sharingan vision.
Of course, this whole reasoning is made with the idea of Pt1 Gai being <<< War arc Gai, because if this is war arc gai, his reflexes are enough to react to Zabuza's mist even without something like sharingan.
Neji and Lee take haku med diff and then go help Gai, and neji's byakugan is a key against Zabuza so team Gai wins, but pt1 Gai is not taking on Zabuza alone.
