Very pleased with form builder. What will it cost to take payments with jotform? Do you provide Gateway and Merchant Account?

We do not charge our users from their payment submissions, it would be enough to pay any suitable plan for your businesses, such as how many payment submissions you need. Payment submission limits are marked in below image.

Also we provide various of payment methods to our users without any additional cost, beside the cut which the gateway it self make.

I recommend you to check following guides of our, which may help you about the topic:

1. Setting Up Your First Order Form - Know the basic on how to setup an order form.

2. Difference Between PayPal and PayPal Pro - If you have a merchant account in PayPal and would like to use it, you can find this article useful in which one to use.

3. Payment Forms Section - This section of our User Guide might be of a help when your looking for basic to advance tutorials that might be of a help to you.

If you have any further questions, please ask us.

Is the cost of the Gateway included in Jotform subscription? or do we have
to pay the online payments provider?
...

You can receive payments through JotForm using provided payment integrations on the form builder. You need to create an account in the gateway in order to integrate and receive payments via JotForm. They may have pricing strategies independently from JotForm.

Our users who have even the free account can receive up to 3 payment submissions monthly. If you want to receive more payment submissions per month, then you need to upgrade your account.

You can see payment limits for different types of accounts above as my colleague showed or you can view our pricing and features here.

Also, you can find payment related guides here. Check it out. 

If you think any explanation I made is unclear, you can contact us anytime.