Did it become easier to land an academic job in the UK after the Brexit referendum?
Fro the anecdotal evidence referred to by Venkatraman Ramakrishnan it appears that there are people who do not want to come to the UK post-Brexit. In your question you are implying a conjecture that the number of applications will fall and there will be easier to get an academic job in the UK.

The conjecture seems wrong to me. You seem to ignore the fact that the number of jobs in academia is not constant. Many jobs are funded by research councils in the UK but also EU councils like ERC. If this funding is going to reduce, so will the pool of available jobs. 

Teaching-focused academic staff are funded by the Universities directly and this funding depends on student recruitment numbers. There is a certain rise in the numbers currently following the cap lifting in 2014 but it won't last forever and can't compensate for the expected reduction in EU student numbers. 

Even if Universities disclose their records of application numbers for the academic posts (which is not likely), this information has to be compared also with the number of posts being advertised. Bear in mind also that with pound weakening, UK jobs are becoming less attractive for overseas applicants even on purely financial grounds.

To summarise, it is possible that the application numbers reduce and it becomes harder to secure an academic job post-Brexit.