Form helper in codeigniter autoescapes form data?
form_submit gives you a <input type='submit'> style button. The value="" field in <input> does not allow you to use HTML in it, so its not CI escaping, its your browser.
In order to use <input type='submit'> submit buttons with HTML, you'd better use <button type='submit'>Your text with HTML here</button>, but you have to write the HTML by yourself.
Update. It is escaped. HTML helper source code. Shouldn't just be looking at forms. Oh well, but the solution above still applies.