However this isn't ultimately the most useful metric. Would you for example select a restaurant based on the reviews and the cuisine or to total annual revenue of its parent company. If your metric suggests you forego surf and turf at a local diner in order to eat a Whopper you may be asking the wrong questions.
For your consideration here is a better one. A language is alive when its ecosystem is likely to receive enough interest and talent to continue to develop enough to allow its users to continue to accomplish useful goals. Being embedded in 2 of the top platforms and being able to reuse those libraries is a factor. Relying on these host platforms means that it can remain alive indefinitely while being useful to only thousands instead of millions as long as it drives enough interest to pay the salaries of the dozens who develop the core and the hundreds that write useful tools.
A stepping stone to more mainstream languages perhaps? I hardly saw a Clojure program so please elaborate.
Like most(ly dead) languages, it still has its followers, in the case of clojure, mostly a cultish group (my impression from r/clojure and other forums).
Going back to 2010 we see less than 500 respondents and only 27% using it for work. A charitable assumption is that it grew substantially between 2010 and 2015 and held steady between 2015 and 2020.
Edit: To clarify, Clojure is mostly a dead language that didn't have any innovations by itself, but it did influenced many programmers(the creator is good at marketing). It helped push forward the FP mindset into the users of other mainstream languages(js, python, java).