Recently published data suggests that between 61 and 133 million Americans may have pre-existing health conditions.
The US government's Department of Health and Human Services, in its updated analysis, has stated that between 61 and 133 million people non-elderly Americans may have some pre-existing health conditions like cancer, diabetes, asthma, high BP, etc. Meanwhile, The Center for American Progress in its report has said that according to new estimates, it is higher, at 135 million people under age 65. It warned that the insurer could use pre-existing health conditions to discriminate against the people in the absence of ACA protections. A 2019 analysis from KFF, a nonpartisan health policy organization, estimated in 2018 that at least 53.8 million adults had pre-existing conditions that would make them unable to buy insurance. Another study, conducted by Avalere, a health care consulting firm, estimated that 102 million Americans had pre-existing conditions that would make them unable to buy insurance.
Based on the evidence stated above, we conclude that the number of people could be between 60 - 100 million. Hence, the claim is partly true.