What kind of files can be attached in a survey and what is the maximum capacity per file?

The default file extensions types that are supplied and accepted are:

pdf, doc, docx, xls, xlsx, csv, txt, rtf, html, zip, mp3, wma, mpg, flv, avi, jpg, jpeg, png, gif

You can allow all files by adding an asterisk "*" in Extension box inside of Form Builder. 

More about File Types/Extensions you can find inside of this guide:

https://www.jotform.com/help/29-How-to-Change-the-Allowed-File-Types-Extensions-in-the-Upload-Field 

Default size of upload field is 1MB. Maximum upload size is 1GB. However please note that free account have only 100 MB of upload storage space. 

Changing the upload size limit

This guide can help you to create upload forms:

https://www.jotform.com/help/332-How-to-Create-Upload-Forms 

Hope this will help. Let us know if you need further assistance.