Uploading Image to s3 turns to horizontal always
Without knowing the origin of your images nor the s3f module I'm rather guessing  your problem consists of the two following parts:


the EXIF data of your images probably contains information that says 'this image should be displayed horizontally
the s3fs module or actually drupal's image module respects the information about the image orientation – but that's different from your expectation (could also be that the problem is that the info about the orientation is not respected)


According to this I would suggest you try either (or both) of the following: 


try to strip the EXIF data in case you don't need it, for example by saving "websafe" from Photoshop or the like
Try to 'teach' drupal the correct exif orientation – for example by using the EXIF Orientation module.