What does cleave mean with regards to a pan of batter?
The English definition of "cleave" is to split or sever something (at least according to Google, Webster has a slightly different take on it).

So, in a cheesecake recipe, it makes sense to me that it is asking that you pour the batter continuously, not in parts. I doubt such a thing would make a huge difference, but consider that it is a Japanese recipe. If such a thing could be expected in a recipe, I would expect to see it in a Japanese recipe.