That is a very open ended question so it shouldn't be that surprising that the results are like this. What part of the response are we talking about? Are we talking about whether it is justified for Israel to respond at all? Are we talking about whether the severity of their response is warranted? Who the fuck knows! Probably a lot more of the people who interpret it as the first would agree with the poll.
The propaganda is how this will be presented as 70% of Americans being pro-Israel, which this poll does not demonstrate.