Since 1998, Gallup has asked Americans whether they believe the government should "redistribute wealth by heavy taxes on the rich." This year, 52 percent agreed, tying the all-time high set in 2013. While there's plenty of disagreement about who exactly counts as "rich," a bare majority of the country seems to think we should be soaking them. (I couldn't agree more.)
The margin of error on the poll is +/- 4 percentage points, so, yes, it's possible that less than half the country is really in favor of steep taxes on the affluent.* But Gallup has now reached the same result twice running, and these findings are in line with the outcomes of similar surveys from Pew, which has found that 54 percent of Americans think the government should "raise taxes on the wealthy and corporations to expand programs for the poor," and that 58 percent say "upper-income Americans pay too little in taxes." Of course, I imagine these answers would look a bit different if the polls focused only on likely voters. In general, Gallup finds that poorer and younger survey takers are more on board with wealth redistribution than older, high-income respondents. In other words, demographic groups who reliably show up at the polls are a bit less fond of confiscatory tax schemes than the country writ large.
*Update May 5, 2015, 2:51 p.m: I updated this post to note the margin of error in the poll. Leaving it out was a bit careless.