I think it's a very pretty name. I do think that a lot of people will associate it with Billie Eilish, but I don't think that's SO terrible. There are worse associations out there, and at least it's an actual name with a separate history from the well-known person who bears it, and it sounds like a normal name.
I love this name I think it’s really cool. Yeah it’s super associated with Billie Eilish but I love her music. I would probably like to name my daughter this but I’m a little bummed because it’ll remind people of Billie and that seems weird.
The person I know with this name says it "uh-LEESH" like the American pronunciation of Alicia or Felicia, but without the a at the end. (I initially thought it was "Alicia" until I saw it written.)
My real name is Eilish, and it's definitely pronounced so that it rhymes with 'fish'. Although, my mum says that I pronounce it wrong. Plus, it is the best name ever.