Comment by random_visitor

Varies from subreddit to subreddit. This is purely anecdotal but on a big subreddit it's usually like 1 in 100 submissions linking to external site get the to "serious traffic" level of traction. You can instead write the same content as a subreddit post and add a link to your site at the end, such posts will have a much higher chance of reaching the subreddit frontpage.