Emotional support is often in the eye of the beholder. For some, it's mutual understanding and encouragement. For others, it is the expression of empathy through verbal reflection. For others, it is something else.
For emotional support in general, I tend to offer a mix of the above until I hit something that sticks. For emotional support and critique in photography, it depends on what someone is asking for. Apart from the gear threads, there are often threads like, 'I'm in a slump' or 'I can't get motivated to shoot' or 'I want to do X but I don't know how'. These are, by nature, emotion-based topics which can be handled as such.
As an example, a recent thread here was about the culling of decades of work. My response was to say something along the lines of, 'that must have been very difficult but ultimately rewarding for you', and then shared my perspective. Honestly, I can't imagine getting rid of my old work as so much of it is documentation of my life, something I highly value. But not everyone shares that value, so I reflected back the sentiments expressed, and tried to put myself in the shoes of a fellow photographer who wanted a clear slate and to retain only what was important.