Mmm. I note that Gilgamesh's hairstyle shifts depending on which costume he's in. In his casual-wear he uses during UBW, he's got a sort of floppy "devil may care" haircut. His Pimped Out Majesty look from Fate and HF, however, features the spiky hair. Also, seen here, Gil's hair comes back up in sort of an odd flame shape, while Archer's hairstyle here simply continues the spiky slicked back look all the way down, looking more akin to a certain blue hedgehog.
However, Nasu is a canny bastard with his parallels, and given the game introduces us to Gilgamesh first as "Archer" before he confirms his own identity, it's entirely possible that Gilgamesh was intended to draw parallels to Archer upon his first appearance while still being completely different, which are only reinforced when Unlimited Blade Works and Gate of Babylon are respectively shown to do almost the exact same thing.
---
"Oh, silver blade, forged in the depths of the beyond. Heed my summons and purge those who stand in my way. Lay
waste."
However, Nasu is a canny bastard with his parallels, and given the game introduces us to Gilgamesh first as "Archer" before he confirms his own identity, it's entirely possible that Gilgamesh was intended to draw parallels to Archer upon his first appearance while still being completely different, which are only reinforced when Unlimited Blade Works and Gate of Babylon are respectively shown to do almost the exact same thing.
---
"Oh, silver blade, forged in the depths of the beyond. Heed my summons and purge those who stand in my way. Lay
waste."