[Facts] Re: Pronouncing the name "Stephen"
Stephen is traditionally "stee-ven" in English. However, people from other cultures may not be familiar with this. I once had a Korean student insist that Stephen must be "steff-en" and only Steven was "stee-ven." Also, in various European languages the name is pronounced "steff-en" or "steff-on" or "shtef-on" (German), so Europeans may carry this over into English as well.
I don't think you could pin anything down to one region of the U.S., though.