If I starve myself,and only consume cigarettes,how long would I live?

Depends. People have been known to survive for 10 days without water, but not much longer.
I wonder why you used the word "consumed" rather than "eat" or "smoke"? Seems an awfully big word for someone who uses "kind of", so I assume you meant to be ambiguous. Not cute, not clever.

PLEASE DON'T DO ANYTHING TO YOURSELF I DON'T EVEN KNOW YOU, BUT I COULD SAVE SOMEONE'S LIFE!!!! YOUR HEART WOULD JUST STOP AFTER A WHILE AND YOU WILL DIE AND YOUR LUNGS WILL TURN ALL BLACK!!!!I S THAT WHAT YOU WANT?? NO DON'T STARVE YOURSELF PLEASE!!!! YOU CAN LIVE A VERY HAPPY LIFE IF YOU PUT YOUR MIND TO IT JUST TRY AND BE HAPPY INSTEAD OF HATING YOURSELF SO MUCH!!! OH AND SORRRY MY CAPS LOCK IS STUCK ON.

A.) Dont even think about commiting suicide. I came up with a saying. "When the world seems to have turned against you, friendship is the only thing can really trust." So turn to your friends and family when you're depressed.

B.) You would not live long AT ALL if you consumed cigarettes. The chemicals in them would begin immediate damage to your body.