For some clients, survival is success. You might be killing yourself more or less slowly through various means connected to addiction or self-hatred, shame, or who-knows-why. In this case, survival comes first.
It might be a marriage or relationship or family that is threatened with extinction or extreme dysfunction and if the parties to the relationship want to grow together, its survival is first.
First you have to survive, and you might come to therapy fighting threats to your survival that scream to be taken care of. If you yourself can read and understand these words, you have survived up to this point; thriving is at least a part of your goals. We might be working both on surviving and thriving at the same time. They go together like people and relationships.
“Survival and Thrival are both yoked to the adaptive evolutionary aim of emotions, negative and positive, respectively. Just as the evolutionary adaptive function of the negative emotions (anger, fear, disgust, etc) is survival, the evolutionary adaptive function of the positive emotions (awe, joy, pleasure, curiosity, gratitude, interest) is thrival… the capacity to thrive or flourish by the expansion of the adaptive capacities of the self” Diana Fosha, “Turbocharging” the Affects of Innate Healing and Redressing the Evolutionary Tilt, 2015.