According to Pew Research Center, which carried out the survey, it is "the first time in a Pew Research Center survey there is as much strong support as strong opposition to gay marriage. In the current survey, 22% say they strongly support allowing gays and lesbians to marry legally; an identical percentage (22%) strongly opposes gay marriage. In 2008, there was about twice as much strong opposition to as strong support for gay marriage (30% vs. 14%).
Since 2004, there has been a broad-based decline in opposition – including strong opposition –to gay marriage. In 2004, Americans younger than 30 were divided (48% opposed, 45% favored). Today, young people favor gay marriage by more than two-to-one (65% to 30%). Opposition has declined by the same percentage – 18 points – among those 65 and older; still, a majority (56%) of this group continues to oppose allowing gays and lesbians to marry legally. Strong opposition has declined 18 points since 2004 among those 65 and older (from 46% to 28%) and 14 points among those younger than 30 (from 28% to 14%)."
Continue to read the survey here.