model1=gr.Interface.load("huggingface/gpt2")

For each model variable, such as model1, please add gr. before Interface.

app.py

@@ -4,7 +4,7 @@ from gradio.mix import Parallel
 myfirstvariable="My First Text Generator"
 mylovelysecondvariable="input text and submit."
 
-model1=Interface.load("huggingface/gpt2")
+model1=gr.Interface.load("huggingface/gpt2")
 model2=Interface.load("huggingface/EleutherAI/gpt-j-6B")
 model3=Interface.load("huggingface/EleutherAI/gpt-neo-1.3B")