Can only humans act?

Digital effects will make Robert De Niro look decades younger in his new Scorsese movie.
For me this raises interesting questions about the essence of acting. We’ve long been able to create backgrounds and scenes with CGI that are nearly impossible to distinguish from ‘the real thing.’ So where does the acting happen? Facial expression? The body? The tone and inflection of the the actor’s voice? If an AI captures and then perfectly reproduces De Niro’s voice, is that acting? Will we notice or care? Are we close to someone (some thing) passing a cinematic Turing Test?