20,000 daily unique website visitors is a pretty good amount and 20,000 daily unique visitors equals to around 600,000 monthly unique visitors so you should be making some good money from Adsense depending on the cost per click of the ads and your CTR "Click Through Rate".
My website gets 300,000 unique visitors per month and makes around $2,500.00 to $3,000.00 per month through Adsense so you should at least make $2,000.00 per month or even $5,000.00 to $6,000.00 per month with 20,000 daily unique visitors which is 600,000 monthly unique visitors.
But again it depends on the niche your website or blog is in and your ad placement and CTR.
You certainly should be earning a monthly payout though through Adsense with 600,000 monthly unique visitors.
Also you'll need to be on a VPS, Cloud Server or Dedicated Hosting for that amount of visitors per day and month.
I would go with cloud servers and cloud hosting though because you can scale your resources as your traffic climbs with just ordering a new hosting package.