Sealioning is not at all the same thing as a Gish Gallop. A Gish Gallop is throwing out very weak arguments or evidence (so, bullshit) faster than a sincerely-engaging opponent can address them. Sealioning is a much more deniable tactic, relying on "just trying to have a conversation" and playing the victim when others disengage or tell you to fuck off.

Simple Sealioning example:

Sealioner: "Do you have anything to back up those figures for holocaust deaths? I see that thrown around a lot and I'm just not sure" (absolutely being a disengenuous piece of shit who's trying to slyly push holocaust denial, but indistinguishable from someone who is in fact curious, aside from that actually-curious people don't end up in these kinds of exchanges half as often as lying assholes do)

Other person who knows exactly where this is going: "Fuck off out of here with that shit."

Sealioner: "Oh my, I was just trying to ask a question. Now I'm really not sure about your position. You seem very touchy about it for someone who has the truth on their side. Can anyone help me?"

A Gish Gallop of the same thing would be throwing out "references" to holocaust denial stuff faster than they can be debunked (and dutifully ignoring the debunking).