If they didn't and just cloned her voice, it's more disregard for creators and artists than I would have thought possible. What were they thinking?
Edit after reading the official story... not sure I believe it, seems disingenuous, at best they chose someone because they really really sounded like Scarlett Johansson, and no one said, it might be a problem.
https://openai.com/index/how-the-voices-for-chatgpt-were-cho...
Voices such as Shatner or Walken are at least as much about speech patterns than the voice, giving you another axis to compare voices against, so I can somewhat see those as being trademarkable. But when I hear the ChatGPT voice, it just sounds like "slightly-flirty generic female voice 03" to me.