Did the invention of the cotton gin lead to the civil war?

Hmmmm .......
Sort of, but it is a tough argument to make.
Perhaps because the cotton gin made a vast spread of cotton plantations possible and therefore made slavery a bigger factor in the economy of the United States than it would have been otherwise, it was a contributing factor to the friction between the slavery dependent states and the states which ran industries manned by free labor.
http://www.civilwar.org/resources/civil-war-history-how-the.html

Thank You.

You are welcome.