In an effort to provide clarity to this evolving situation, here is the link to the Executive Order issued by Governor Cuomo. https://www.governor.ny.gov/news/no-205-quarantine-restrictions-travelers-arriving-new-york
There will be implementing emergency rule making by the Commissioner of the Department of Health.

One question has been what does it mean to "enter into New York"? In the context of air travel you have entered New York when you have exited the area of the airport terminal where access is controlled by the TSA security screening. In other words, if you have landed at a gate and transfer to another gate without passing the point at which you would require additional TSA screening, you have not "entered New York". However, it you pass the point at which you would require TSA screening to enter a secure airport space, you have "entered into New York". For example at JFK, if you need to change terminals or get on the Airtrain, you have entered into New York and are subject to the requirements of the Governor's Executive Order.

I hope this helps. This is not meant to stoke partisan comments.