Welcome to the Revolution Pi community!
There seems to be support for simulink with Raspberry Pi (https://de.mathworks.com/hardware-suppo ... ulink.html
), so maybe this would work on the RevPi too (besides the extension modules). But I cannot say for sure, as I don't have any experience with Simulink.
Regarding your questions about a Connect with 8 GB of memory: Not with the current available devices (Connect + or Connect S/SE), but next year we will release the Connect 4 which will be also available with 8 GB of RAM.
Hope this answers your questions.