If a PhD student kills himself, how does that affect the advisor? Does it count against him for tenure purposes?
To get the elephant out of the room first:
If you are contemplating suicide and wondering whether you will hurt the tenure case of your advisor by this, stop this thought right there and get counselling. The tenure case really is of no concern in this question. I am sure your advisor would also agree to this.
Now, assuming that this is a hypothetical question, or it concerns a suicide that already happened.
A suicide of a student will very likely not hurt a tenure case directly. No educated person in her/his right mind would react like "he killed this guy, he must be the worst teacher ever!" I would rather expect a wave of sympathy and compassion about the loss. Of course, whenever a student leaves (for whatever reason), the tenure case is indirectly hurt a little, simply because the advisor needs to start from ground up with a new student, who is likely not going to be very productive for some time.
I'm quite sure that for most professors, their own tenure is about last in the things they care about in this situation. Professors are people too, they care about their students and how they do. In some sense, your students are your children too, as you see them grow up and spend a lot of time together. You're proud if they succeed, and you're sad if they struggle. If a student kills themselves, from the perspective of the adviser it's first and foremost a human tragedy. The impact on the tenure case is really something that's secondary (or tertiary, or even less important).
There is no obvious link between a student suicide and the supervisor's tenure. As you may know, even a breaking up with his/her boy-/girl-friend can lead to a suicide.
If you are planning to punish/revenge your bad-ass supervisor, there are more than 100 ways, but none of them would be a suicide. If he/her has ever abused/hurt you, just report to the committee, and you may find that someone even help you punish him/her.
If the tragedy has happened to your student, please first make sure not to blame on yourself too much -- unless you really helped a lot on the tragedy -- a suicide is also a decision of him/herself.