This quote has a long history and its true origins are obscure.
I began my investigation of this question by doing a web search for
quote speaking truth wants publish journalism marketing. In the results, among a lot of serious discussions about journalism, was a Goodreads page which attributes the following quote to George Orwell:
“Journalism is printing what someone else does not want printed: everything else is public relations.” ― George Orwell
Actually I do think this sounds a lot more like George Orwell than Oscar Wilde. The former had worked as a journalist, but also described journalists (in Homage to Catalonia) as people who lie for a living. So my next search was for the exact quote cited in the Goodreads article.
The top result on that search was "Even if it looks, sounds, walks, and quacks like an Orwell quote, it still might NOT be an Orwell quote" (25 September 2012), a blog post which points out that it's hard to track down this quote as really being from Orwell. One of the links on that page was to the Wikiquote talk page about George Orwell, where several contributors were trying to track down an original source for this quote, Orwellian or otherwise. One user claimed (29 June 2012) that the original version is due to William Randolph Hearst:
“News is something somebody doesn't want printed; all else is advertising.” - William Randolph Hearst
Another user found (24 November 2012) a similar quote from Alfred Harmsworth, Lord Northcliffe:
"News is what somebody somewhere wants to suppress; all the rest is advertising."
Yet another user found another similar quote from Horacio Verbitsky (in Spanish):
“Journalism is to spread what someone does not want you to know; the rest is propaganda.”
And finally - finally! - someone linked to the Quote Investigator page on this quote, from 20 January 2013. Quote Investigator, by the way, is an absolutely invaluable resource for answering quote-identification questions here: they do really in-depth research to puzzle out the true origins of a quote, and everything is properly sourced and verifiable. So here's the final answer.
A version of this quote first appeared on 30 November 1918, in page 18, column 4 of The Fourth Estate: A Newspaper for the Makers of Newspapers, Ernest F, Birmingham, Fourth Estate Publishing Company, New York. The quote is as follows:
“Whatever a patron desires to get published is advertising; whatever he wants to keep out of the paper is news,” is the sentiment expressed in a little framed placard on the desk of L. E. Edwardson, day city editor of the Chicago Herald and Examiner.
For the further history and evolution of this quote, including the many other variants of it and people it's been attributed to, you can read the full Quote Investigator article. Hat-tip also to Barry Popik, whose blog post of 11 July 2014 helped Quote Investigator to improve their article.