You are mistaken to say Israel has never declared any borders. On 14 May 1948, when Israel declared statehood under UN resolution 181 it declared that sovereignty within precisely delineated borders as spelled out in meticulous detail in Part II of the resolution. UN 181 was activated when Israel declared statehood. The resolution said Jews living in Palestine and Arabs living in Israel could become citizens of the country in which they reside. UN 181 did not say what percentages of territory each state would hold. The illegal Israeli blockade on Gaza is not determined by borders. Israel has imposed collective punishment on a civilian population. That act is a violation of article 33 of the 4th Geneva Convention. It is a war crime.
from the article: Year after Gaza war, Hamas says ready to fight Israel again