Stats is not maths? How mainstream is the claim that stats is not maths? And if it's right, how many people don't agree? 
Given that it's all numbers, taught by maths departments and you get maths credits for it, I wonder whether the claim is just half-jokingly meant, like saying it's a minor part of maths, or just applied maths.

At my university, the departments are separate. While they have a bit of interaction (i.e. we share a restroom on the second floor), there is very little contact between the two departments. This is true from the earliest freshman classes, clear through to professorial research. The two departments really do not interact. So while the subject matter may be similar ("numbers"), for all intents and purposes, the two fields might as well be totally separate.
One other thing I note is that to get a math degree at my institution, one needs to take a single stats course. In fact, only one stats course can even be counted towards a degree in math. That is the most they will count. But, the stats department requires multiple math courses to earn a degree (BS) in stats. 
My personal view on the matter is that stats is a branch of applied math, much like earning a degree in Korean is a branch of linguistics; but, much of the lingual theory of the latter is avoided in earning the former.  
