In Naruto if Danzo has the Sharingan is he a Uchiha?

Not always. The only way to get the sharingan if you are not an Uchiha is to have a medical ninja transplant his sharingan eye into their own. I would say he is not an Uchiha because an Uchiha would have a sharingan eye in both eyes, while Kakashi and Danzo only have one Sharingan eye.

He is not an Uchia he took an uchia's eye that is very powerful especially with powers of persuasion. He also has many sharingan eyes on his right arm (i think ten) and the first hokages cells in him so he can use izinagi (not sure how to spell that name might be wrong) which alows him to make any wound or death a dream. In other Words he can make it so he was never hurt. (he can't fully do it though but Tobi who is actually madara can use it well-for five minutes. danzo can only use it for one minute).