What is the cause for too little or too many patients in a hospital? I'm currently at lvl 7 I think, 3rd year is on and I've only had 50 ish patients so far. I have 40k in loan and I'm still operating in negative $$$. Is there a way to get more patients in? and is there a strategy to get less patients when in need?

You can get some info on that in one of the statistics views (the one with the pie chart). Basically the more they like your hospital, the more of them will come.

As for less patients, I never really wanted that. Either I had enough money so I could keep on building stuff for more patients, or I didn't have enough money and I wanted more patients to come :) You could always just send them to different hospitals though (or home).

but how is it possible to get barely any patients at the start of the game. my case was in the first 3 years i got just over 50 patients in total. i did not have bad rep since it is not even possible to have that bad rep at the start.

What I usually do at the start of the level is to set the speed to slowest, click that green button so that patients can start coming and then I start building. AFAIK patients will only start coming when you have a reception desk, so start with that and when you're done with the building just set the speed back to normal. You can basically have your hospital up & running around 5th January

You should check the pie chart for the 'market share' as well. Do the other hospitals get way more patients than you? If you're around 25% then this level simply hasn't got that many patients.