Let me be clear, he does not. For one, his political associations alone casts a tremendous amount of skepticism over this statement.
More importantly, his conception of the two-state settlement runs in contravention to the international consensus. He has said that he wants to maintain all or some of the settlement blocs (the ones he definitely wants to maintain are the very largest of them, namely Ariel, Gush Etzion and Ma'aleh Adumim). So he won't adequately even define what the "Palestinian State" would be, he insists on settlement inclusion, he insists on said Palestinian state being demilitarized, he bitches about all the "threats" Israel faces while wholly ignoring the much bigger threats Palestinians face, etc.
Furthermore, he's stated numerous times that he would only insist on negotiations with the Palestinian Authority, which is a completely illegitimate entity that does not speak for the Palestinian people, and they've been known not to for decades. They were created via a concession by Arafat in the Oslo negotiations, largely because it was the life preserver that Israel and the US were willing to throw to him after tacitly supporting Saddam Hussein in the first Gulf War. It has since been maintained despite the fact that they were defeated in the 2006 elections and continue to do so mostly through intimidation, coercion and violence. This would be akin to some Arab leader saying that they'd only negotiate with the US via the Tea Party.
Bottom line, this has nothing to do with the two-state settlement as it's understood by the vast majority of the world. That consensus includes, among other things, to quote the Peaceful Settlement of the Palestine Question:
The Palestinians will never recognize those settlement blocs, which means they will never recognize whatever "borders" Lapid proposes.
Yeah, Lapid is absolutely opposed to this. That advisory opinion, which to repeat was unanimous when you consider what Buergenthal said in his separate declaration, deemed that all segments of the wall in the West Bank that were built in Palestinian territory as a means to protect Israeli settlements are, to quote Buergenthal, "ipso facto in violation of international humanitarian law" and that those segments of the wall must therefore be dismantled.
Again, that can't happen when Israel is proposing preservation of illegal settlements.
Lapid insists on maintaining large swaths of that territory.
Again, opposed.
You get the idea.
What he has said about it is akin to when David Bar-Illan said back in 1996, "If Palestinian sovereignty is limited enough so that we feel safe, call it [the Palestinian State] fried chicken." It's that same dismissive, imperialist attitude that Bibi has about it. Again, they're changing the style. Not the substance.
Just as a guide, if what Israel is proposing falls shorter of the international consensus than the Clinton Parameters did, it's a non-starter. Lapid knows that.