I admit that this is a much higher number than I expected.
But there's nuance there. First, look at the date. This is about a poll in July 2014, this is very explicitly NOT about the latest, massive push by Israel.
Second, there's fluctuation in the support based on what exactly is going on (and of course based on what Hamas has done recently).
Third, the poll is only among Jewish Isrealis (which are the majority, but you're still missing about a quarter of all Isrealis in this).
Last but not least: this is a monthly poll by some think tank. I don't know anything about this specific think tank, but I'm cautious taking single polling by one organisation which may or may not have biases or an agenda as the only source of truth. Even just changes in phrasing can massively influence the results.