It depends on which style you are using.
When using the Chicago Manual of Style and AP style, the word “with” should always be lowercase in a title unless it is the first or last word in a sentence. This is because “with” is a preposition which according to title capitalization rules are always lowercase in titles.
However, in APA and MLA styles, the word “with” is capitalized because all words longer than 4 letters are capitalized.
To find out what other words are always lowercase in a title, try out our free title capitalization tool.