There is as such data available to determine how many candidates appeared in the LFAT exam 2020.
The cut-off for previous years Round 1 category-wise was -
General - 182.4
SC - 152
ST - 116
OBC - 172.8
You can assume the cut-off for this year will be more or less the same/similar to previous years'. As this is just an estimation based on previous cut-off I would suggest you to check official website.
For more information -