Yes, he is on Kaido's level. Doesn't matter that Kaido "ran through a gauntlet of several people", because Luffy technically too ran through a gauntlet fighting Kaido while powering up. A healthy Nika fighting Kaido from the beginning is very different from a Luffy that was eating a lot of unnecessary blows in weaker states while also dealing weaker blows to Kaido in the journey of powering up.
Gives me Oj flashbacks...