If you have no delays, in landing or in getting out of the airport, you should have plenty time enough. The railway station is part of the airport building with the platforms under the floor of the central arrivals area.
It takes about 5 minutes from where you pick up your luggage to the platform. Follow the 'train' signs and then look on the screens which platform to go.
If your train ticket is part of your airline ticket, the train company should honor it even if you are late due to the flight being delayed or the airport being slow for whatever reason.
Thalys is usually good in honoring tickets if you have a delay which you could not do anything about. It is not guarantied that they will honor a flight delay or an airport mess-up in passport control if you have a separately bought ticket, but if you are missing your train, go to one of the railway staff and ask.
If you miss your train and need to buy a new ticket, Thalys tickets are in the €80 range for 'same day' buys, but busy trains may be more expensive. The less fast 'intercity trains' cost €45 and take an hour longer, but will not sell out.