Corn meal is highly absorbant... soaks spilled fuel up really quick. It can soak the spilled fuel OUT of the wood!

You CAN remove the mojority of the fuel that soaked in... and the sooner you start trying the better the result.

Apply corn meal (the stuff used to make cornbread)... then let it sit overnight. Clean it up.

Brush on denatured or rubbing alcohol. (not a lot... ) reapply corn meal. Overnight again. Clean it up.

More corn meal... heat it with the heat gun from the outside. clean it up.

That Should remove over 80% of the fuel that soaked into the wood. (if you started soon enough...)

The longer the fuel was allowed to soak in before removal began... the deeper it got. and the stuff that got deep is there forever.