how to bind two-way radio button in angular 2

For two way data binding its as same as all others use this syntax [(ngModel)]

Replace your code block with below:

<div class="form-group">
    <label>Gender:</label> 
    &nbsp;

    <label class="radio-inline">
        <input type="radio" name="optradio" value='Male' [(ngModel)]="employee.gender" >Male
    </label>

    <label class="radio-inline">
        <input type="radio" name="optradio" value='Female' [(ngModel)]="employee.gender" >Female
    </label>

</div>

You can try this

 <div class="form-group">
                    <label>Gender:</label> &nbsp;
                    <label class="radio-inline">
                    <input type="radio" name="gender" [(ngModel)]="employee.gender"
[value]='Male' [checked]="employee.gender == 'Male'" >Male
                </label>
                    <label class="radio-inline">
                     <input type="radio" name="gender" [(ngModel)]="employee.gender"
[value]='Female' [checked]="employee.gender == 'Female'" >Female
                </label>
                </div>

Also, you forgot to add the [value] property in your inputs and change the name of the input to gender