The current blockade started in 2007 2 years after Israel pulled out of Gaza and Hamas took control.
No? It was turned into its current form in 2007. Gaza has been partially blockaded by Israel (harsh reduction, but not completely termination, of exports) since 2005, and got even worse in 2006.
Following the disengagement, human rights groups alleged that Israel frequently blockaded Gaza in order to apply pressure on the population "in response to political developments or attacks by armed groups in Gaza on Israeli civilians or soldiers".[26] The special envoy of the Quartet James Wolfensohn noted that "Gaza had been effectively sealed off from the outside world since the Israeli disengagement [August–September 2005], and the humanitarian and economic consequences for the Palestinian population were profound. There were already food shortages. Palestinian workers and traders to Israel were unable to cross the border".
They also withheld the PNA's tax income for more than a year, and as for the effects I'll let Wikipedia speak on my behalf.
By releasing or withholding these revenues, Israel was able, in the words of the International Crisis Group, to "virtually turn the Palestinian economy on and off".