As I suspected, looks like something is overridden with the !important at the end of the declaration. If you turn off that rule in the inspector does the width appear as you'd like it to?
If it doesn't, copy the selector for that CSS rule and put a parent class or ID at the beginning. This will override the !important because the rule will have greater specificity than the rule with the !important in it.
<div class='ginput_container'>
<input name='input_3' id='input_1_3' type='text' value='03/05/2015' class='datepicker medium mdy datepicker_with_icon' tabindex='2' />
</div>
<input type='hidden' id='gforms_calendar_icon_input_1_3' class='gform_hidden' value='http://dispatch.dapage.net/wp-content/plugins/gravityforms/images/calendar.png'/></li><li id='field_1_4' class='gfield field_sublabel_below field_description_below' ><label class='gfield_label' for='input_1_4_1' >Time</label><div class='clear-multi'>
<div class='gfield_time_hour ginput_container' id='input_1_4'>
<input type='text' maxlength='2' name='input_4[]' id='input_1_4_1' value='22' tabindex='3' /> <i>:</i>
<label for='input_1_4_1' >HH</label>
</div>
<div class='gfield_time_minute ginput_container'>
<input type='text' maxlength='2' name='input_4[]' id='input_1_4_2' value='25' tabindex='4' />
<label for='input_1_4_2' >MM</label>
</div>
.ginput_container input#input_1_3.datepicker {
width: 50px;
}
.ginput_container input#input_1_3.datepicker {
width: 50px;
}