Based on following example from jaeger docs:

apiVersion: jaegertracing.io/v1
kind: Jaeger
metadata:
  name: simple-streaming
spec:
  strategy: streaming
  collector:
    options:
      kafka: # <1>
        producer:
          topic: jaeger-spans
          brokers: my-cluster-kafka-brokers.kafka:9092
  ingester:
    options:
      kafka: # <1>
        consumer:
          topic: jaeger-spans
          brokers: my-cluster-kafka-brokers.kafka:9092
      ingester:
        deadlockInterval: 5s # <2>
  storage:
    type: elasticsearch
    options:
      es:
        server-urls: http://elasticsearch:9200

and on example cli falgs:

--kafka.producer.topic	jaeger-spans
The name of the kafka topic
--kafka.producer.brokers	127.0.0.1:9092
The comma-separated list of kafka brokers. i.e. '127.0.0.1:9092,0.0.0:1234'
--kafka.producer.plaintext.password	
The plaintext Password for SASL/PLAIN authentication
--kafka.producer.plaintext.username	
The plaintext Username for SASL/PLAIN authentication

I infere that you should be able to do the following:

spec:
     strategy: streaming
  collector:
    options:
      kafka: # <1>
        producer:
          topic: jaeger-spans
          brokers: my-cluster-kafka-brokers.kafka:9092
          plaintext:
            username: <username>
            password: <password> 

Notice that I split the cli options with the dot and added it as a nested fields in yaml. Do the same to other parameters by analogy.