No, they are not on the same level.
In the fight with Base Gerard, Gerard deliberately takes damage to become a giant
His other feat is to be able to hit Gerard who Toshiro froze. Since Toshiro froze all his abilities and features, it would be wrong to scale Byakuya to FP Gerard.
Besides, he has anti-feats that show that he should not scale to Gerard:
He felt the need to open Bankai against Robert.
He felt the need to escape Candice's attack.
In the anime, he could not destroy the creatures (I don't know what their names are) that fell from the Soul King's palace. He could destroy them in the manga version. But this was changed in the anime version.
In my opinion, Byakuya should not be scaled even to Final form Yammy, but it is extremely difficult to get this accepted here and put it in the profiles. We have already discussed it.