There is lot more information and clarity with regards to this that needs to come out. Bloggers would need a GST registration in the first instance.
Many people talk about the earnings below the ceiling limit of Rs 20 Lakhs but fail to realize that blogging services become interstate supply and this needs to be declared. The direct ads bloggers place on their websites also attracts GST because, the person who asks for the ad to be placed becomes the service receiver and the blogger who places the ad on his/her site becomes the service provider. If you provide a service and get paid for it by raising an invoice, then you need to think of paying GST.
If you are applying for a commission, again by raising an invoice, you need to pay GST. Many bloggers have their own website, if there is any e-commerce activity in your name like e-books, selling of ad space on your website, displaying sponsored post for which you raise an invoice to get paid, these require to GST to be paid.
With regards to google adsense, many feel that the blogger need not pay GST as he or she does not decide on the ad that is displayed. It is done by google and the service request comes from a company that pays google directly.