As far as I'm aware, legal experts agree there is no way to compel you to lie. Apple's general counsel has said on the record he doesn't know what Bloomberg are talking about, so how would they even verify this gag order was proper?

https://twitter.com/dnvolz/status/1048283980913684480

Note that he volunteered to be on the record, he could have said that off the record or made no comment at all.