Starvation does not equal famine, nor does famine stem from lack of food. There has also been plenty of deathes from malnutrition, likely enough to qualify for a famine by most metrics.
At any rate, the Israeli Defense Minister's description of the blockade in October was, “We are putting a complete siege on Gaza … No electricity, no food, no water, no gas – it’s all closed.” So yes, Israel, without a shadow of a doubt, purposefully blocked food importation into the Strip. Whether it constitutes the actual crime of starvation is another matter, but pretending that Israel didn't block food imports is like denying the sky is blue.