I suspect the Central Powers win, but it's not a sweeping victory.
Eagle v Shark = CP totally demolish the Entente until they reach the beaches
M1 CP cut off all trade with British and their allies. All British shipping in American and CP ports are seized crippling the merchant marine. Commerce raiders begin starvation blockade of British Isles
M15 Germany and Italy launch invasion of France and Belgium
M15 Serbo-Bulgarian border war frees Austrian troops to face Russia
M23 Russian offensive begins with 53 division invading Austria
m40 Germans, advancing at a leisurely pace reach Marne. French launch last ditch counter offensive. Fails. British forces begin to make a run for the Channel
M60 Russian assault on Austria reaches 90 divisions. Mass surrenders and desertions deplete Austrian ranks
M75 France and Austria sue for peace. Turn over all heavy weapons and naval forces to Central Powers Central Powers now have absolute hegemony over the continent and the seas
Seriously
Russia destroys Austria and Germany beats France, Belgium and the British OTl in the first six weeks of war. The only thing that saves Austria is the Russians sending forces against the Germans. Same for the Western powers. If the Germans aren't pressed for time, have to divert forces against Russia and have the Italians backing them up, how are Britain, Belgium and France lasting past the Marne?
Even if we generously allow for the French and Austrian fleets to flee to Britain, how is Britain going to hold out? There won't be anyone to trade with even if by some miracle they could keep the sea lanes open