Hitler (or at least some in the German High Command) did want to close the Straits of Gibraltar. In fact, preliminary negotiations took place with Franco on German troop movements through Spain, but Franco flatly refused and the plan was dropped.
Taking that into consideration, do we assume that further negotiations would have borne fruit and allowed German forces free passage through Spain, or do we assume that Spain would resist a German invasion?
Thanks steveegg. Your two questions lead me to a third.
Can we assume that the Germans could have taken it regardless of what Franco wanted?