1984 reeks of Brave New World and We by Yevgeny Zamyatin ;-)
In all seriousness though... Originality can be the idea, the execution, the twist, the angle, the new perspective. Or it can just be 1984 for millenials. I dont know.
The themes from 1984 (of privacy and control, etc) and even the images and language (big brother, thought crimes...) have so permeated culture (and reality) that similar concepts aren't even necessarily derivative anymore. It's part of the zeitgeist. It's just out there. (It's nearing cliché, but most of it is saved by its relevance.)
It's like any mafia story reminding one of The Godfather.
It has become foundational to how we think and talk about similar broad ideas.