Is vitamin b1 deficiency something that leads to a bigger hangover?

Probably. This hasn't been well-researched but is probably the case. Regular heavy alcohol use is associated with b1 deficiency which can cause alcohol-related brain damage. B1 plays a role in metabolizing alcohol. Many people have found that taking b complex vitamins reduces hangover symptoms. However, hangover is a sign of toxicity from excess alcohol use; I strongly advise limiting alcohol to 2 drinks/day.