您可以使用WITH clause来计算已连接节点的数量，然后根据此计数进行过滤。
如果要将传入连接指定为Round

MATCH (rnd:Round)<-[:IN_ROUND]-(a)
WITH rnd, count(a) as incomingNodes
WHERE incomingNodes>5
RETRUN rnd

如果要同时计算传入和传出连接：

MATCH (rnd:Round)-[:IN_ROUND]-(a)
WITH rnd, count(a) as connectedNodes
WHERE connectedNodes>5
RETRUN rnd

您可以使用类似于以下内容的内容：

MATCH (n:Round)<-[:IN_ROUND]-(:Answer)
WHERE size((n)<-[:IN_ROUND]-(:Answer)) > 5
RETURN distinct(n)

您可以看到它对以下示例数据有效：

MERGE (a:Round{key: 1})
MERGE (b:Round{key: 2})
MERGE (c:Answer{key: 3})
MERGE (d:Answer{key: 4})
MERGE (e:Answer{key: 5})
MERGE (f:Answer{key: 6})
MERGE (g:Answer{key: 7})
MERGE (h:Answer{key: 8})
MERGE (i:Answer{key: 9})

MERGE (c)-[:IN_ROUND{key:1}]-(a)
MERGE (d)-[:IN_ROUND{key:1}]-(a)
MERGE (e)-[:IN_ROUND{key:1}]-(a)
MERGE (f)-[:IN_ROUND{key:1}]-(a)
MERGE (g)-[:IN_ROUND{key:1}]-(a)
MERGE (h)-[:IN_ROUND{key:1}]-(a)
MERGE (i)-[:IN_ROUND{key:1}]-(b)
MERGE (c)-[:IN_ROUND{key:1}]-(b)
MERGE (e)-[:IN_ROUND{key:1}]-(b)
MERGE (f)-[:IN_ROUND{key:1}]-(b)
MERGE (g)-[:IN_ROUND{key:1}]-(b)

正在返回：

╒═════════╕
│"n"      │
╞═════════╡
│{"key":1}│
└─────────┘