My own thought is - every artist in history has taken inspiration from previous artists. The British voice actor in the above example surely studied greats in his field like Sir Patrick. We don't typically mind that. Where I think the line is between standing on the shoulders of giants and devaluing someone else's art is how well digested, for lack of a better term, the inspiration has been. Is the later artist breaking the components out, examining each, and assembling them with the insights they gained? Or are they seeking to resemble the end result as much as possible? I think that separates the cheap hack from the person who 'steals like an artist'