Yes, but they need to contain an embedded PDF compatible file/stream. When we open .ai (Adobe Illustrator) files into our apps, we actually open and display the embedded PDF compatible file/stream.
If you open an .ai (Adobe Illustrator) file that doesn't contain an embedded PDF compatible file/stream, you will get the following message:
This is an Adobe Illustrator File that was saved without PDF Content. To Place or open this file in other applications, it should be re-saved from Adobe Illustrator with the "Create PDF Compatible File" option turned on. This option is in the Illustrator Native Format Options dialog box, which appears when saving an Adobe Illustrator file using the Save As command.