That function evolve_bootstrap() is in evolve-plus/library/functions/basic-functions.php line 1367
Something must have gone wrong when you are updating your theme. I guess you updated it using ftp and that file must be missing or empty. Please re-upload evolve-plus/library/functions/basic-functions.php again.
We shall see if you still have other fatal errors.
screenshot of the file. http://prntscr.com/7ppdgt