Her - https://www.youtube.com/watch?v=Ij0ZmgG6wCA
If it was a soundalike then it would be a legal issue obviously, nothing to discuss.
Looking at the HN comments they are told it sounds like Her so that's what they believe. So you can't trust the NPC's to decide, they just regurgitate media headlines.
How do you quantify it?
But I have tried many times. It does sound similar to me. Ask her to recite poetry with natural pauses and expression.