Kirk posted on Instagram in March 2024 that "The 'Great Replacement' is not a theory, it's a reality." Alongside this statement, Kirk shared a screenshot from a Fox News story headline that read; "7.2M illegals entered the U.S. under Biden admin[istration], an amount greater than population of 36 states." After Elon Musk was widely criticized for endorsing an antisemitic post that referenced the Great Replacement Theory and blamed "Jewish communities" for supporting mass migration, Kirk defended Musk, stating that "Jewish communities have been pushing the exact kind of hatred against whites that they claim to want people to stop using against them."