How far would you agree that it was mainly help from outside that made the Nationalist victory in the Spanish Civil War possible?

I would completely agree because the nationalists got help from Italy, Germany and Portugal to fight in civil war. They sent arms, men and supplies such as food and raw materials. Mussolini provided 70,000 troops and a transport aircraft to transport the troops across Spain and Morocco. Hitler provided tanks and allowed airforce to bomb undefended civilian targets.
Republicans received help from Russia but the deciding factor was that France and Britain did not interfere because of the agreement to be neutral, though Italy and Germany had also signed the agreement but they did not keep the agreement and supported Nationalists in the civil war.