This is in no way any criticism or anything like that, lussy is really good at this.

How do you kill them and tank them so easily?

Killing them "easy" is due to his fleet/alts (they're not on his pvp overview), there is more DPS going on than just the Leshak. He is tanking easily because the Leshak is not primary all the time, and certainly not by all of them. I don't know the opponents fit, but for instance that rattle shouldn't have died that easily if goodfit and probably would have eaten the Leshak alive in a 1v1 under that phobos scram. Anyone can correct me on this if i'm wrong, i haven't used the new ships yet.

As with any PVP in EVE it also comes down to circumstance and also some "pick the right fight", which is a real valuable skill in EVE. In order to read situations correctly experience is needed, and to get experience one have to die, a-fucking-lot.