No, I do not know if Farzad Kamangar is still alive.
Tonight I happened to read this letter from him.
No, I do not know, if it is authentic and - given it is - how he'd been able to write it and 'smuggle' it out of his cell.
However, having spoken to two (renowned) Iranian writers once being tortured in Iranian prisons, I tend to rely on the letters authenticy and its contents.
Well, read and judge yourself.