Getting members from views

My sub is getting really good views right now, over 7 million in March but it is still only at around 20k members. What’s the best way to get more people to join the sub.

Most of the stuff posted on it is from me with only a couple of posts started by others, wish I could encourage these viewers to post more.

Pin a post asking lurkers to join and contribute, people love feeling invited

Great amount of views
If you want more members, you could pin a post as Natsuko suggested and also cross promote your subreddit in similar subreddits, relevant for your niche