1
I think listening is preferable than reading.
I think listening is preferable to reading.
Use preferable to, not preferable than: ‘Travelling by train is preferable to driving.’
2
Fish is always more preferable than meat.
Fish is always preferable to meat.
Preferable already means ‘better or more suitable’, so do not use more before it.
To make the meaning stronger, use much preferable or far preferable: ‘The first option is much preferable to the second.’
See PREFER