Gap is Luffy having G5 and future sight.
I would have to disagree for a couple of reasons:
1. Luffy had FS before Wano and it made no difference, Luffy had G4 post DR and it made no difference.
2. Number of powerups is not the deciding factor, because then Garp has no business competing with the likes of Roger, WB, Kaido etc.
3. ACoC was not the only powerup that Zoro got
Let me explain a little more. When we get to Egghead the first thing we see is how strong Zoro's weakest attack (Bird Dance) has become without ACoC, compare his BD against Hody in FI, then against King in Wano and the latest in Egghead to cut the eddy. Zoro also uses Enma to deliver the attack without any showing of a drawback. Zoro's base AP has heavily grown.
Next we get to Zoro waking from a nap and blocking Kaku's attack. While Lucci vs Luffy callbacks were easily recognized, this one was not done so much. Firstly that in EL Zoro was sleeping when he met Kaku and in his sleepy state he mistook him for Usopp, here the setting is the same, Zoro is sleeping on the ship. Next is that Kaku launches his signature attack (his finisher in EL) on the ship from quite a distance. Zoro not only wakes up but also blocks the attack. Zoro's CoO has reached an entirely new level, even when WB has sleep diffing Ace, Ace was in close proximity unlike Kaku who launches the attack from a distance.
Thirdly we have seen the M3 use their Wano powerups in Egghead. Luffy has used Gear 5, Sanji has used Exo and Zoro has used Overflowing Ryou (which some retards are calling KoH). Thing is we never saw the Overflowing Ryou mode get its own separate showing in the King fight (which is partly responsible for the confusion). Overflowing Ryou is Zoro's G5 equivalent (in terms of counting powerups), KOH on the other hand is a combination of Overflowing Ryou + Overflowing ACoC and is on an entirely different tier.
I think there is a very real chance that Zoro won't get FS like Luffy but another variation of CoO some sort of ultra instinct coupled with his BOAT like how Luffy got ID CoA and Zoro didn't because the two are very different in style of combat and having same powerups would be boring for the two most popular characters in the manga. Its like Goku and Vegeta where Vegeta doesn't get UI but UE, powerups but different to suit the style of the wielder.