The example quote sounds like "This's gotta be the worst job in the world."
which is short for "This has got to be the worst job in the world."
"This is gotta be the worst job in the world." is grammatically incorrect. I assume it is an incorrect transcription.
"This's gotta be the worst job in the world." and "This has gotta be the worst job in the world." are very informal. "Gotta" is not acceptable in formal written text, but is common in informal speech.
"This has got to be the worst job in the world." is emphatic in an informal context. It is marginally acceptable in formal contexts.
"This has to be the worst job in the world." is formal. People who say "gotta" consider "gotta" to be more natural than this expression.
"This must be the worst job in the world" is formal. To my (American) ear, it sounds less natural than "This has to be the worst job in the world" or "This has gotta be the worst job in the world."
"This is the worst job in the world." is formal, and acceptable in informal speech. Unfortunately, it does not give the same impression as the other forms do. (The other forms suggest that the speaker has tried to imagine worse jobs, and failed.)
gottawas used? I thought gotta is ususally used as a slang equivalent ofgoing to have toorhave gotwhich have obbligation meaning. – Dmitrii Bundin Mar 01 '15 at 18:49