That depends. Most of the time, police won't do anything. But if the person DID actually kill themselves after you told them to, and ESPECIALLY if you've harassed them for long periods of time then there may be real life consequences. The police will most likely consider ALL the factors that lead to suicide, not just a simple "go kill yourself". They might reconsider it if they were sexually abused, their family is dysfunctional, or you tried to hurt them physically as those can be much bigger factors. Lots of times, cyberbullying is just the last straw. They can't take it anymore after being through other traumatic experiences.
So yes, it is possible to be charged for cyberbullying in the long run. In jail? Probably not, especially if you're still a child. Like I said, it depends on so many things that happened.