I noticed this post which is close to what I want, http://forum.gravityhelp.com/topic/hide-the-submit-button-conditionally, but not exactly. What I want to do is disable the submit button, not the data that is contained within the form.
The website is behind a firewall on an intranet, so I can't give you the link, but here is the source for the form.
Since there is no id for the the submit button, I am not sure how to do it.
<div class="gform_wrapper" id="gform_wrapper_1">
<form method="post" enctype="multipart/form-data" id="gform_1" class="" action="">
<div class="gform_heading">
<h3 class="gform_title">Got something to share with the rest of us?</h3>
</div>
<div class="gform_body">
<input class="gform_hidden" name="is_submit_1" value="1" type="hidden">
<ul id="gform_fields_1" class="gform_fields top_label"><li id="field_1_2" class="gfield"><label class="gfield_label" for="input_1_2">Subject<span class="gfield_required">*</span></label><div><input name="input_2" id="input_1_2" value="" class="small" tabindex="1" type="text"></div><li id="field_1_3" class="gfield"><label class="gfield_label" for="input_1_3">Phone<span class="gfield_required">*</span></label><div class="ginput_container"><input name="input_3" id="input_1_3" value="" class="medium" tabindex="2" type="text"></div><li id="field_1_4" class="gfield foobar"><label class="gfield_label" for="input_1_4">Tell us more:<span class="gfield_required">*</span></label><div><textarea name="input_4" id="input_1_4" class="textarea small" tabindex="3" rows="10" cols="50"></textarea></div>
</div>
<div class="gform_footer top_label"><input class="button" value="Tell Us!" tabindex="4" type="submit">
</div>
</form>
</div>