is there anything like tracing 2D image to model in Siemens NX8?

Yes there is.

  1. Step 1:

    Go to... View > Visualisation > Raster Image

  2. Step 2:

    The Raster Image dialogue box pops up with all the options.
    Click on 'Specify TIFF image'

  3. Step 3:

    As you've already noticed only TIFF files are supported, use your favourite image editor to convert your images to TIF format.

    Pick the image you want.

  4. Step 4:

    Now you've chosen the image, you now have to create the Raster image in the model view by clicking on 'Create Raster Image'

  5. Step 5:

    Then the Image will appear in the model view.
    Use the options to resize, set transparency and manipulate position and angle using the Trident handles.

  6. Step 6:

    Apply! Then you're ready to sketch.