Americans picked Soviet leader Mikhail S. Gorbachev as one of the 10 most-admired men, according to a Gallup Poll. President Reagan topped the list and Gorbachev tied for eighth place with Chrysler Chairman Lee A. Iacocca in the survey, conducted shortly after the signing of the U.S.-Soviet missile treaty last month. Pope John Paul II, who also visited the U.S. last year, came in second. Democratic presidential candidates Rev. Jesse Jackson and Gary Hart tied for third place, followed by Vice President George Bush, evangelist Billy Graham and Marine Lt. Col. Oliver L. North. Former President Jimmy Carter was 10th on the list.