+1 NRG I think is T1. When NaVi went through a rough stretch they were still considered T1 for the most part. I think continental bias is what is directing his "t3 at the most" talk.
There is no hard and fast T1, T2, etc. ranking. It's really up to individuals and the community what constitutes a "tier". My personal evaluation says that at a certain tier any of the teams can beat each other, but rarely gets beaten by someone at a lower level. Astralis is basically on a level of their own, but you can't really say they're Tier 1 because they're up there by themselves. Under them are 4 or 5 times that can beat each other but shouldn't lost to those under them. I'd say they are Tier 1 (and include Astralis in that group, even if they are basically unbeatable).
T1 = Astralis, Liquid, Navi, NRG, Faze, MiBR, and at the moment perhaps ENCE.
T2 = Those that aren't realistically going to be going to finals but can make some close series. Mouz, NiP, Renegades, FNatic, Vitality, etc .
T3 = Those teams that haven't broken through yet. They may be on the rise and may rise to T2 or may fall and never make it... like Avangar, Cloud9, G2, Ghost, Complexity, etc... and yes; Furia