Do I need to have 400k in my bank account for a visa if I am married to a Thai citizen?

you have zero financial requirement you are a woman just the fact that you are married is enough

If you are legally married to a Thai male there are no financial requirements

There is no financial requirements for foreign female married to a Thai male, but there might be some additional requirements to your Thai husband. Go to your local immigration office to get the latest handout of their requirements and check what he needs to provide.

This is a sample of in-country visa application from the website of Immigration Bureau HQ. What is acceptable could be immigration office-specific(or even whether required or not).