The gensim function in MATLAB is typically used to generate a Simulink model from a Simulink Control Design linear model (say, models created with the Linear Analysis Tool). However, for integrating a deep learning model dlnetwork into Simulink, gensim isn't directly applicable because dlnetwork objects are not linear models and don't directly convert into Simulink models through gensim.
To integrate a dlnetwork object block into Simulink, the approach would be to define the dlnetwork object in a MATLAB function block that takes inputs compatible with your dlnetwork, performs a forward pass (using predict or forward), and returns the output. You can also refer to this answer on how to use dlnetwork from MATLAB in Simulink: https://www.mathworks.com/matlabcentral/answers/1611315-how-can-i-use-a-dlnetwork-type-neural-network-from-matlab-in-simulink
