Last week’s vice presidential debate reinforced voters’ earlier impressions that Dan Quayle was less qualified than Lloyd Bentsen to serve as President, if the occasion arose, a survey by the Gallup Organization has found. Democratic attempts to make political capital out of George Bush’s choice of running mate appear to have failed. Bush’s Republican ticket now leads Michael S. Dukakis’ Democratic slate by 49% to 43%, statistically unchanged from results of a pre-debate trial heat, according to phone interviews with 1,007 registered voters Friday through Sunday. The survey had a 4% margin of error. The debate enhanced perceptions that Bentsen was qualified to be President, from 68% in a pre-debate poll to 76%. Quayle advanced from 34% to 46%.