Rather than building a string of your HTML in JavaScript code nested within an evaluate tag, you can use Jelly to build your markup.
The idea is to first use <g:evaluate> to grab the data you want to be included in your output HTML and store that in some sort of data structure. The g:evaluate part of your script can essentially be the "preprocessing" part, which is responsible for obtaining some sort of data that you want to display. That data can then be looped over using a <j:forEach> to build your HTML <table>
For example:
<?xml version="1.0" encoding="utf-8" ?>
<j:jelly trim="false" xmlns:j="jelly:core" xmlns:g="glide" xmlns:j2="null" xmlns:g2="null">
<!-- Add your first <g:evaluate> here but change it to a <g2:evaluate> --->
<g2:evaluate jelly="true">
var stakeList = jelly.jvar_incidentgr.u_impacted_user_list.getDisplayValue().split(', ');
</g2:evaluate>
<p>Names</p>
<table>
<tbody>
<j2:forEach var="jvar_impactedUser" items="$[stakeList]">
<tr>
<td>$[jvar_impactedUser]</td>
</tr>
</j2:forEach>
</tbody>
</table>
</j:jelly>
You can make the stakeList array hold more sophisticated data, such as objects to hold related data. You can then add additional columns to each row (<tr>) in your table by adding an additional <td> to output any other associated data. You can refer to MDN's article on styling tables if you want to add additional cellpadding/spacing or a border.
In the above example, I'm using a g2:evalaute as it will recompute the HTML each time the UI page is loaded, as opposed to a g:evaluate that caches the rendered HTML output and doesn't update it on subsequent reloads. It's up to you decide which is best for you, but if you're using g2/j2, then you need to use $[] instead of ${} when accessing variables.
In addition, I suggest checking out Chuck Tomasi's YouTube guide on Jelly scripting, the links can be found at the top of the Jelly Scripting documentation in the ServiceNow docs.
