AWS: Cloud Formation: Is it possible to use multiple "DependsOn"?

Yes,

The DependsOn attribute can take a single string or list of strings.

http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-attribute-dependson.html

Syntax:

"DependsOn" : [ String, ... ]

Yes, "DependsOn" can take multiple strings. I have listed an example below:

"DependsOn": [ "S3BucketAppElbLogs", "ElbLogAppBucketPolicy" ]

This answer comes up first in Google, so I will include how to do multiple dependson attributes in YAML, which I found in this answer.

AnotherProductionResource:
  Type: AWS::CloudFormation::Stack
   Condition: ISProduction
   DependsOn:
   - AResource
   - MyProductionResource
   Properties:
     [...]