Gothics are a strange breed. They go out of their way to attract attention to themselves...and then they bleat and bray when they're stereotyped, and picked on.
Did you want the attention or not, asshole?
And most gothics kill themselves for the attention. Half of them are just 'crying out for help'.
The best thing you can do for someone crying out for help, via a suicide threat: Ignore them. Don't give them the attention they're craving. Make them find out the hard way that the real world doesn't give a shit if you're sad, or depressed.