In which two ways would control over italy the allied forces

Italy is a very central position in Europe. Even though it is surrounded by sea, when it comes to air attacks, it is close to all the eastern European countries.

Having Italy would cause Mussolini to be removed from power. It wouldn't grant land access to many regions, the allies could have done a few things with this territory:

They would be able to launch air attacks on Germany

and also

They would gain control of the Mediterranean Sea

the tallest building in the western hemisphere and the sixth tallest building in the world