I need to come up with a thesis statement for a research paper I chose to write regarding "the influence of women on theatre from 1700 to today" I...

"Influence of women onfrom 1700 on to today" is a very broad topic, so you
will want to narrow it down.  A good thesis statement should provide an assertion or opinion
about your topic and supporting subpoints that can act as your main body paragraphs. 

So the most important step for you is to narrow down your topic.  What is is about the
influence of women on theatre from 1700 on to...