About 70 percent of those polled predict lifting the ban would have positive, mixed or no results.
The survey is based on responses by some 115,000 troops and 44,200 military spouses.
"It's shown what many of us have known all along, that gay and lesbian people should be allowed to serve openly in the military," said former Marine Jim Key, who is also a spokesman for the L.A. Gay & Lesbian Center. "Not only do the majority of Americans believe that, but also the majority of service members."
Republicans led by Sen. John McCain are opposed to a repeal.
"To somehow allege that this policy has been damaging to the military is simply false," McCain said.
Defense Secretary Robert Gates and the chairman of the Joint Chiefs of Staff both support repealing the law.
The Associated Press Contributed to this report.