Pretty sure Evelyn Waugh pronounced it Eevlin. He was male.
Don't know how his first wife pronounced it. She was also called Evelyn. They were known as He-Evelyn and She-Evelyn. They split up. Don't know if the name thing was a factor.
Anyway, I digress. I'd probably assume Eevlin first of all, but I've come across both Ehvlin and Evalinn.
(People are saying Everlin because most English people don't pronounce the r in Ever so to them it sounds the same as Evah. They completely fail to grasp that to those us who do pronounce the letter r this is incredibly distracting.)