Yes , Azure AD Graph API support batch processing on users . Please refer to this code sample , check the CreateUsersTest function in that code sample . To make that sample work , you need to add Read and write directory data app permission for your client app :

Another way is to use powershell to add multiple users using a bulk import process:
first create a csv file with appropriate attributes like :

Then you could install Azure ActiveDirectory Powershell (MSOnline).
Connect the service :
PS C:\WINDOWS\system32> connect-msolservice
Import users from csv file :
$users = Import-Csv E:\a.csv
Create users with New-MsolUser command .
$users | ForEach-Object {New-MsolUser -UserPrincipalName $_.UserName -FirstName $_.FirstName -LastName $_.LastName –DisplayName $_.DisplayName -Title $_.JobTitle -Department $_.Department -Country $_.Country}
Update :
Please refer to document : https://msdn.microsoft.com/en-us/library/azure/ad/graph/howto/azure-ad-graph-api-batch-processing
The Graph API supports a subset of the functionality defined by the OData specification:
A single batch can contain a maximum of five queries and/or change sets combined.
A change set can contain a maximum of one source object modification and up to 20 add-link and delete-link operations combined. All operations in the change set must be on a single source entity.
In your scenario ,a single source entity means one user entity , you could create a user , modify that user in a change set , but can't create two users in one change set, since they're two entities .
It seems there is no such document lists rate limiting for batch process , but i have tested create 2000+ users with above code and it works fine .