Yes! We've been running Milvus in production for about three years now, powering some customers that do have queries at that scale. It has its foibles like all of these systems (the lack of non-int id fields in the 1.x line is maddening and has required a bunch of additional engineering by us to work with our other systems), but it has held up pretty well in our experience.

(I can't speak to Milvus 2.x as we are probably not going to upgrade to that for a number of non-performance reasons)