yes you can.
its used on bbpress.org , its not in button format but yeah
first you create a new page called New Topic
put the shortcode [bbp-topic-form]
into that page.
now to create a button , im just going to show you how to create a link with a background so it basically is a button.
put the text widget in your sidebar
and put this html in it.
<a class="bbp-new-topic-button" href="http://yoursite.com/new-topic" "title="Create A New Topic">Create A New Topic</a>
and put this CSS wherever you can put custom CSS
a custom css plugin
jetpack custom css module
in the bbpress.css file that you could copy to your child theme.
in your child themes CSS stylesheet
a.bbp-new-topic-button {
color: #fff;
font-size: 24px;
background: #222;
padding: 10px 20px;
border: solid #222 2px;
text-decoration: none;
}
a.bbp-new-topic-button:hover {
color: #222;
background: #fff;
}