Gnosis is more than just a term and is often quite controversial, particularly to those that do not actively practice it. There are specific practices (generally not divulged in public, but on a one-to-one basis and always for free) on techniques that allow one to verify for oneself the truth of pretty well anything /everything.
This does not appear to be one of those, but rather is formed by a collection of psycotherapists, asking for rather sizable donations. Authentic gnosis will never have fees. These people have a 'free consultation' followed by $100 individual fees for family support, from what I can make out.
Not in Greek, though. I've never seen it used in English before, so I couldn't say about that.