"In many TEFL hotspots, especially Korea and China, demand for teachers far outstrips supply, meaning finding a job is more of a question of when rather than if."
More: Teaching English abroad is an increasingly popular choice for struggling graduates - Study Abroad - Student - The Independent
"when rather than if" means what?
If you say "if I find a job" then there is doubt about whether you will find a job.
If you say "when I find a job" then there is no doubt that you will find a job.
If that many teachers are demanded, then it is a question of "when" not "if" a person finds a job as an English teacher.