If you can't get in via filezilla then you are entering the wrong information in the settings area of filezilla. Has nothing to do with the site being live or not. Just need a valid hosting account. Check in your hosting account for the correct FTP settings.

Or just upload your file with CPANEL file manager and don't worry about FTP.

I wanted to reconfirm - just for your info for building wordpress site, like creating new page, information - you don't need to access via filezilla. Wordpress has their own backend for you to set things up.

You only need filezilla if your uploading or trying to modify the core files of wordpress or directly uploading mass images or replace existing theme design files.

If you need more help, please PM me.

The problem is your FTP account and you have 2 options:
1) Is not connecting and if is so then Filezilla will tell you
2) Is connecting but your FTP account is not pointing to the right directory.If the FTP account is created by you make sure you didn't created a directory with your FTP account name and the new account points to that folder.Normally your account should point to your "public" folder and this way you'll have access to all of your websites from that hosting account.You can solve this from your cPanel.

You mean your website is working fine, but you are not getting any data through FTP ?

Does your ftp user have access to the website folder ?