$('#btn__AddEmployee').click(function() {
const checked = $(this).prev().prop('checked');
$('#table__Employee tbody').append(`
<tr>
<td>
<input type="checkbox" ${checked ? 'checked="checked"' : ''}>
</td>
</tr>
`);
});
или
document.querySelector('#btn__AddEmployee').addEventListener('click', e => {
const input = document.createElement('input');
input.type = 'checkbox';
input.checked = e.target.previousElementSibling.checked;
document
.querySelector('#table__Employee tbody')
.insertRow()
.insertCell()
.append(input);
});