That robot performs sedation, not general anaesthesia. Sedation provides a slight depression in awareness and pain sensation, and is much easier than full general anaesthesia, in which the patient is completely paralysed, unconscious, and insensate. General Anaesthesia generally requires intubation, a complex practical procedure which can go wrong very quickly, and kill people very quickly. It requires close monitoring of numerous parameters, some of which are digital measures (blood pressure, heart rate, etc) but others are quite subjective, such as the patient's appearance and the current stage of the surgical procedure.
The claim that this device is a replacement for an anaesthatist is similar to claiming that an automated wheel balancing machine will one day replace car mechanics. Certainly it can perform one specific component of one kind of anaesthesia, but it is far cry from the full skill set of an anaesthatist.