Can I use the same antenna for GSM and RF433 MHz?
Theoretically, you can design a multi-band antenna and use it for both GSM and 433MHz receiver. To combine the two radios to the same antenna you would need a diplexer, which could be implemented using a low-pass filter feeding the 433MHz receiver and a high-pass filter feeding the GSM radio.

However, if you have enough space, I strongly recommend that you use two separate antennas. It will be much easier to design each antenna and you won't need additional circuitry to combine the two radios.

For PCB trace antenna I recommended using the inverted-F topology (IFA). They are simple and relatively easy to tune. You should be able to find reference designs in the web.