We try not to watch stats or programs to figure out the website but rather trust God and His purpose. We encourage saints who are not to consider to pray daily for this ministry: https://www.sermonindex.net/modules/newbb/viewtopic.php?topic_id=53973&forum=16&4
How many daily/monthly visitors?
I believe its over 10,000
How much GB is sermon index hosting?
Almost 300 GB
and about 1 TB of video files on Youtube
How many people are listening to sermons at any given time?
I counted once a few years ago that daily over 15,000 sermons are downloaded so it should be much more now.
Many other sites link to the sermons also which we continue to promote, we are not trying to build a kingdom or empire but want the messages to freely go out to as many as possible for the expansion of God's kingdom. So many sites have added hundreds of our messages, we encourage saints to do this and add them to their blogs, social media, facebook etc.
To God be the glory great things He is doing!