Yes, you can run both your controller and a heating element from a single 120VAC circuit. You will need to determine what amperage your power circuit is (or can be). I would recommend at least a 20A circuit breaker, preferably the GFCI type. That circuit would require #12 AWG wiring. This would be fine with a 1500W element (12.5A) for your RIMS tube and your controller (the datasheet I found for it only showed a 50mA current draw at 120VAC). If you choose a 2000W element (16.7A), you'll be getting close to capacity and will be exceeding the 80% guideline. You could then choose a 30A (GFCI) circuit breaker, but would need to ensure that the circuit is wired with #10 AWG wire.
Another style of readily available terminal blocks are below. I use what's called a power distribution block for my panel that has 240VAC, 50A incoming hot, hot, and neutral wires, along with a ground block for the grounds. This is an easy way to distribute multiple, smaller gauge wire circuits from a single, larger incoming circuit. See an example below.