You asked what Europe can fund the war with. The euro zone has a $20 trillion dollar GDP and extensive domestic manufacturing so it’s not clear why you think they need gold to use their own tax revenue.
Ukraine isn’t Europe. Ukraine doesn’t have euros , gold, grain or minerals (out of the ground). And the men have been killed , so they don’t have any way to get that to pay for the weapons
You asked “What can europe fund the war with?” Did you mean to write “Ukraine” instead of “europe”? Otherwise it seems weird to say that the EU can’t take euros, give them to manufacturers in the EU, and disagree the weapons to Ukraine.