The seized battleships and Ottoman entry into the First World War

Were the Ottomans already likely to join the Central Powers, or did Britain's seizure of their battleships decide the issue?

Both mattered: the government already leaned toward the Central Powers, and the seizure strengthened the war party.

Ottoman entry into the First World War did not have a single cause. The government was already inclined toward the Central Powers before the battleship crisis. Britain's seizure of the Ottoman ships nevertheless helped the faction pressing for war. Remaining independent of the alliance blocs would have been the preferable strategic course in this assessment.