Yes, wiki pages within wiki library can be migrated from SharePoint 2013 to SharePoint Online using SPMT tool.
For example, wiki page in Site Pages library can be migrated to SPO as shown below(this is my sample test):
However, publish pages(except default error page) in Pages library will not be migrated, it will be skipped:
Although the Wiki page library has no additional features to activate, in SharePoint Online, we recommend that you use modern pages instead of classic pages (wiki pages).
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