I assume you speak about the third step, that if you suspect existence may meaningless, you might as well assume it has a meaning, because if you were correct it doesn't matter that you are wrong anyway (by definition).

I don't think it's like Pascal's wager, because there's no need for probability here, and you're not trying to avoid any bad outcome. I think it's more like how Pascal rejected the concern that he might be insane (if you ask yourself "how do I know I'm not crazy?" you're basically already assuming you're not crazy).

But, I haven't actually read all of Pascal's Pensees. What extracts I have read of it suggests to me that he's heavily straw-manned both by later philosophers and people writing about it today, so for all I know the "wager" was more like this, too.