Were I rich, I would live on Long Island.
If I were rich, I would live on Long Island.
Is the first sentence still used, or is used in particular contexts (in example, to give emphasis to the sentence)?
It's rarely used nowadays (in the US at least). It will usually come off as sounding stilted in everyday speech, but possibly more educated/sophisticated in formal speaking and writing (but even then, should probably be used sparingly).