How much consultant or subject expert is paid for recording a lecture or session as a part of online course?

Depends, a software development course would pay somewhere around 15-20K. Data Science/ML/AI around 20-25K, and sometimes can go as high as 35K as well for a one hour of recorded lecture. Here you will be required to prepare the content all by yourself, from scratch without any plagiarism, and it usually takes 8-9 hours to record one hour of lecture including the feedback iterations. Not every EdTech company pays this though. Majority of them go to a maximum of 10-15K for one hour.