The Guaranteed Income Supplement is income-tested meaning if you have more than the maximum allowable net income you may be disqualified from receiving the benefit. The maximums vary depending on your marital status and if you or your spouse receive the full amount of OAS.
CRA has a handy chart that shows the limits for each situation. Here's the link: https://www.canada.ca/en/services/benefits/publicpensions/cpp/old-age-security/payments.html
