Only 1500 people participated which is basically nothing. How can that possibly be representative of a country of ~300mil? The questions say "Have you heard of Qanon?" and "Do you like Qanon?", but doesn't clarify what Qanon is... For all we know those 30% of people polled heard "Qanon is a movement against the Democrats" and thought, "Oh, I like that." They did not sign up for 'satan worshipping pedos'.
Without seeing their methodology, there's no reason to believe the information is accurate. How did they confirm people submitting answers were really who they say they are? And YouGov is a British company which I've never heard of, not a criticism but it does make me suspicious.
There's so many problems with surveys like this, but instead you jumped immediately from "Business Insider said this" -> "30% of Republicans are conspiracy theorists."