If Jones has any hope of being re-elected he will vote to acquit because he knows if he votes against Trump he knows he’s dead.
Jones has no chance of getting re-elected. Republicans know that any senator that’s elected for SIX YEARS is more emboldened because he knows that for six years he can’t be touched, and will vote with democrats on almost everything if not everything. It’s a heck of a lot better to have a republican senator that doesn’t look to block the president or the republican agenda. For six years, Jones would be a hindrance to any part of the republican agenda.