Only income earned from working is considered for the earned income credit. Other types of income, like Social Security, rental income, investment income etc. do not increase the amount of income used to calculate your EIC. They do, however, factor in your AGI which affects the amount of EIC you can receive.
The IRS offers a tool to help you estimate your EIC:
https://www.irs.gov/credits-deductions/individuals/earned-income-tax-credit/use-the-eitc-assistant
https://www.irs.gov/credits-deductions/individuals/earned-income-tax-credit
The amount of EIC you are receiving can be seen on your Form 1040 on line 17a
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**