earned income tax credit / refund

If one is 70 years old, on a small social security, ($10k yearly), and raising one young grandchild full time, and if, perhaps that person had some self employment for a portion of a year, (say, $5-7k), and had not reported or paid any self employment tax, when filing a 2019 tax return, would it 'normally' be of  significant enough IETC benefit to report that income, via an amended return, and pay the tax. I am assuming, based on the very low income (not even the threshold required to file...but was done only in order to receive the stimulus funds), that there would be a decent refund. IE: With whatever late penalties etc., would they still avail of enough EITC to make it worth while?

Is there a formula or chart for something like this?