According to Google Analytics, for the period from 01/01/2019 to 08/28/2019, the blog brought in $ 41.000 (463 payments) for the entire period or $ 5.130 (57 payments) per month.
The blog affects the user at different stages of the purchase decision. Therefore, for a rough assessment, you can use the attribution model, taking into account the time decay attribution model. According to it, the touchpoints closest in time to the sale or conversion get most of the credit.
In our case, the half-life is 7 days, which corresponds to the statistics of blog readers’ behavior. It is clear that this is a rather conservative approach, and if you increase the period, you can get a higher attributed income. At the same time, you need to take into account the general principles of how Google Analytics attribution models work, and understand that such an estimate is approximate.